Distribution transformer operation gear synchronization vector on-line detection method and distribution transformer operation gear synchronization vector on-line detection device

Abstract

The embodiment of the invention discloses a distribution transformer operation gear synchronization vector online detection method and device, and the method comprises the steps: obtaining a nameplate parameter of a distribution transformer, and carrying out the calculation to obtain a short-circuit impedance value of a low-voltage side to a high-voltage side under each gear; synchronously measuring a voltage vector of the low-voltage side of the distribution transformer, an output current vector and a neutral point voltage vector; when the amplitude of the low-voltage-side zero-sequence current reaches a current detection threshold value or the module value of the low-voltage-side neutral point voltage vector reaches a voltage detection threshold value, obtaining a detection loop and combining a circuit principle and a low-voltage-side synchronous voltage vector, a synchronous current vector output by the low-voltage side and a low-voltage-side neutral point synchronous voltage vector of the distribution transformer; calculating to obtain a short-circuit impedance value of the low-voltage side to the high-voltage side; calculating to obtain the absolute value of the impedance difference value of each gear; determining the gear corresponding to the minimum absolute value of the impedance difference value of each gear as the current operation gear of the distribution transformer; the operation gear of the transformer can be accurately detected on the low-voltage side in the operation state.

Description

Technical Field

[0001] The present invention relates to the technical field of on-line detection of transformer parameters, and in particular to a method and device for on-line detection of the operating position of a distribution transformer. Background Art

[0002] As an indispensable key device in the power system, the operating state of a distribution transformer directly affects the safety, stability and economy of the power supply network. The deviation of the tap position of the distribution transformer will cause abnormal output voltage and affect the power supply voltage quality of users. Mastering the operating position of the distribution transformer can provide accurate reference data for the management of user voltage quality, and avoid poor management effects or even incorrect management methods caused by incorrect tap positions. Traditional power-off verification requires power supply interruption, while on-line detection can complete tap verification without power-off, reducing power-off time and economic losses. Moreover, abnormal tap positions may reflect mechanical jamming or electrical connection faults, and real-time detection can provide early warnings to avoid equipment damage. Real-time detection of the tap position of the distribution transformer also provides real-time data support for the automatic dispatching of the power grid, facilitating dynamic voltage regulation and load optimization.

[0003] At present, several patents and technical solutions at home and abroad have explored the detection of the operating state of distribution transformers, but there are still certain deficiencies:

[0004] The patent "A method and device for detecting the operating position of a distribution transformer (CN109061356A)" discloses a method and device for detecting the current operating position of a transformer by detecting electrical parameters (such as voltage, current and their phase changes) generated by the distribution transformer under load conditions, providing an idea for tap judgment based on parameter changes for the existing technology. However, it is necessary to install detection devices on the high and low voltage sides of the distribution transformer, with high investment and operation and maintenance costs, and there are still limitations in its detection real-time performance and accuracy.

[0005] The patent "Distribution transformer and its detection method, system and control of voltage regulation ratio (CN108037346A)" discloses a method and system for calculating the voltage regulation ratio of a transformer by using the primary input voltage, secondary current and phase value, and realizes the detection of the tap state of the transformer through corresponding control. Although it provides a certain on-line detection ability, there are problems such as long data acquisition cycle, large external interference and high cost of measuring the primary input voltage.

[0006] In summary, although certain progress has been made in the current technology, there are still deficiencies in terms of real-time performance, accuracy, system integration, high implementation cost and high difficulty. The present invention calculates the operating position of the distribution transformer in real time using multiple parameters on the low voltage side of the distribution transformer while the distribution transformer is energized, providing strong support for the stable power supply of the distribution transformer and the construction of the smart grid. Summary of the Invention

[0007] The main object of the present invention is to provide a method and device for on-line detection of synchronous vectors of operating taps of a distribution transformer, which can obtain the operating tap of the distribution transformer by real-time calculation of multiple parameters while the distribution transformer is in live operation, and can complete tap verification without power outage, reducing power outage time and economic losses.

[0008] To achieve the above object, in the first aspect of the present application, a method for on-line detection of synchronous vectors of operating taps of a distribution transformer is provided, and the method includes:

[0009] Obtain the nameplate parameters of the distribution transformer, and calculate the impedance value of the low-voltage side to the high-voltage side of the distribution transformer at each tap according to the nameplate parameters of the distribution transformer;

[0010] Synchronously measure the low-voltage side voltage vector, the current vector output by the low-voltage side, and the low-voltage side neutral point voltage vector of the distribution transformer;

[0011] When the amplitude of the zero-sequence current on the low-voltage side of the distribution transformer reaches the current detection threshold, or the modulus of the low-voltage side neutral point voltage vector reaches the voltage detection threshold, obtain the detection circuit, and combine the circuit principle and the low-voltage side synchronous voltage vector, the low-voltage side output synchronous current vector, and the low-voltage side neutral point synchronous voltage vector of the distribution transformer to calculate the short-circuit impedance value of the low-voltage side to the high-voltage side;

[0012] Calculate the difference between the short-circuit impedance modulus of the low-voltage side to the high-voltage side and the impedance value of the low-voltage side to the high-voltage side at each tap of the distribution transformer, and obtain the absolute value of the impedance difference at each tap;

[0013] Determine that the tap corresponding to the minimum value of the absolute value of the impedance difference at each tap is the current operating tap of the distribution transformer.

[0014] Optionally, the calculating the impedance value of the low-voltage side to the high-voltage side of the distribution transformer at each tap according to the nameplate parameters of the distribution transformer includes:

[0015] Calculate the impedance value of the low-voltage side to the high-voltage side of the distribution transformer at each tap according to the following formula:

[0016]

[0017] Where Z i is the impedance value of the low-voltage side to the high-voltage side of the distribution transformer at tap i, with the unit of Ω, U e2 is the rated voltage of the low-voltage side of the distribution transformer, with the unit of kV; U E is the nominal rated voltage of the distribution transformer; U Ei is the rated voltage of the high-voltage side of the distribution transformer at tap i, with the unit of kV; S Nis the rated capacity of the distribution transformer, with the unit of kVA; U X % is the percentage of impedance voltage of the distribution transformer.

[0018] Optionally, the impedance value of the low-voltage side to the high-voltage side at each gear of the distribution transformer is obtained by measuring the short-circuit impedance test of the high-voltage winding to the low-voltage winding at each gear when the distribution transformer leaves the factory or directly measuring the short-circuit impedance of the low-voltage winding to the high-voltage winding.

[0019] Optionally, the distance between the measurement point of the synchronous measurement and the outlet end of the distribution transformer is less than a preset distance threshold.

[0020] Optionally, the method further includes:

[0021] When measuring the low-voltage side voltage vector, the current vector output by the low-voltage side, and the low-voltage side neutral point voltage vector of the distribution transformer, high-precision voltage and current sensors for measuring amplitude and phase angle are used.

[0022] Optionally, the voltage detection threshold and the current detection threshold are determined according to the measurement accuracy of the sensor. The voltage detection threshold is not less than the minimum resolvable voltage measured by the sensor, and the current detection threshold is not less than the minimum resolvable current measured by the sensor.

[0023] Optionally, if the amplitude of the zero-sequence current on the low-voltage side of the distribution transformer does not reach the current detection threshold and the modulus of the low-voltage side neutral point voltage vector does not reach the voltage detection threshold, an adjustable impedance is connected to increase the zero-sequence current.

[0024] Optionally, the method further includes:

[0025] Compare the moduli of the low-voltage side three-phase voltage vectors to obtain the phase with the lowest low-voltage side voltage amplitude, and connect the adjustable impedance between the phase with the lowest low-voltage side voltage amplitude and the low-voltage side neutral point;

[0026] Or, compare the moduli of the low-voltage side three-phase current vectors to obtain the phase with the largest low-voltage side current amplitude, and connect the adjustable impedance between the phase with the largest low-voltage side current amplitude and the low-voltage side neutral point.

[0027] Optionally, the adjustable impedance is a resistor, a capacitor, an inductor, or any combination thereof.

[0028] Optionally, obtaining the detection circuit and combining the circuit principle and the low-voltage side synchronous voltage vector, the synchronous current vector output by the low-voltage side, and the low-voltage side neutral point synchronous voltage vector of the distribution transformer to calculate the short-circuit impedance value of the low-voltage side to the high-voltage side includes:

[0029] When the low - voltage side synchronous three - phase voltage vector, synchronous three - phase current vector, and neutral - point synchronous voltage vector of the distribution transformer are obtained, the short - circuit impedance value of the low - voltage side to the high - voltage side is calculated using the following formula:

[0030]

[0031] When the low - voltage side synchronous zero - sequence voltage vector, synchronous three - phase current vector, and neutral - point synchronous voltage vector of the distribution transformer are obtained, the short - circuit impedance value of the low - voltage side to the high - voltage side is calculated using the following formula:

[0032]

[0033] When the low - voltage side synchronous zero - sequence voltage vector, synchronous zero - sequence current vector, and neutral - point synchronous voltage vector of the distribution transformer are obtained, the short - circuit impedance value of the low - voltage side to the high - voltage side is calculated using the following formula:

[0034]

[0035] When the low - voltage side synchronous three - phase voltage vector, synchronous zero - sequence current vector, and neutral - point synchronous voltage vector of the distribution transformer are obtained, the short - circuit impedance value of the low - voltage side to the high - voltage side is calculated using the following formula:

[0036]

[0037] Wherein, are the three - phase voltage vectors of the low - voltage side of the distribution transformer respectively; are the three - phase current vectors output from the low - voltage side of the distribution transformer respectively; Z 21 is the short - circuit impedance of the low - voltage side of the distribution transformer to the high - voltage side, is the neutral - point voltage vector of the low - voltage side of the distribution transformer; U L0 is the zero - sequence voltage measured on the low - voltage side of the distribution transformer, is the zero - sequence current measured on the low - voltage side of the distribution transformer.

[0038] The second aspect of this application provides an on - line detection device for synchronous vectors of the operating gear of a distribution transformer, including:

[0039] A neutral - point voltage measurement unit, connected between the neutral point of the low - voltage side of the distribution transformer and the ground, for measuring the neutral - point voltage vector of the low - voltage side of the distribution transformer;

[0040] A neutral - point current measurement unit, connected between the neutral point of the low - voltage side of the distribution transformer and the ground, for measuring the neutral - point current of the low - voltage side of the distribution transformer;

[0041] A voltage measurement unit, connected to the low-voltage side of the distribution transformer, for measuring the low-voltage side voltage vector;

[0042] A current measurement unit, connected to the low-voltage side of the distribution transformer, for measuring the current vector output from the low-voltage side;

[0043] A phase-selection switching switch, connected between the low-voltage side of the distribution transformer and the adjustable impedance unit, for connecting the adjustable impedance unit between the phase with the lowest low-voltage side voltage and the ground;

[0044] The adjustable impedance unit, connected to the low-voltage side of the distribution transformer, for adjusting the unbalance degree of the load of the distribution transformer;

[0045] A control calculation unit, connected to the voltage measurement unit, the current measurement unit, the neutral point voltage measurement unit, the adjustable impedance unit, and the phase-selection switching switch, for:

[0046] Obtaining the impedance reference value of the low-voltage side to the high-voltage side at each gear of the distribution transformer;

[0047] Calculating the short-circuit impedance value of the low-voltage side to the high-voltage side;

[0048] Calculating the difference between the short-circuit impedance modulus of the low-voltage side to the high-voltage side and the impedance value of the low-voltage side to the high-voltage side at each gear of the distribution transformer, and obtaining the absolute value of the impedance difference at each gear;

[0049] Determining that the gear corresponding to the minimum value of the absolute value of the impedance difference at each gear is the current operating gear of the distribution transformer.

[0050] The present application provides a method and device for online detection of synchronous vectors of operating gears of a distribution transformer. By obtaining the nameplate parameters of the distribution transformer, the impedance value of the low-voltage side to the high-voltage side at each gear of the distribution transformer is calculated according to the nameplate parameters of the distribution transformer; synchronously measure the voltage vector of the low-voltage side, the current vector output by the low-voltage side, and the neutral-point voltage vector of the low-voltage side of the distribution transformer; when the amplitude of the zero-sequence current on the low-voltage side of the distribution transformer reaches the current detection threshold, or the modulus of the neutral-point voltage vector of the low-voltage side reaches the voltage detection threshold, obtain the detection circuit and combine the circuit principle and the synchronous voltage vector of the low-voltage side, the synchronous current vector output by the low-voltage side, and the synchronous neutral-point voltage vector of the low-voltage side of the distribution transformer to calculate the short-circuit impedance value of the low-voltage side to the high-voltage side; calculate the difference between the modulus of the short-circuit impedance of the low-voltage side to the high-voltage side and the impedance value of the low-voltage side to the high-voltage side at each gear of the distribution transformer to obtain the absolute value of the impedance difference at each gear; determine that the gear corresponding to the minimum value of the absolute value of the impedance difference at each gear is the current operating gear of the distribution transformer; this method can, while the distribution transformer is energized, use multi-parameters to calculate the operating gear of the distribution transformer in real time, complete the gear verification without power outage, reduce the power outage time and economic losses, and avoid voltage fluctuations caused by incorrect gears. Early warning of mechanical jamming or electrical connection failures can be provided to avoid equipment damage, provide real-time data support for grid automation dispatching, and assist in dynamic voltage regulation and load optimization. It provides strong support for the stable power supply of distribution transformers and the construction of smart grids, provides a solution for the digital twin of transformers, and supports the digital transformation of the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only 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.

[0052] Among them:

[0053] Figure 1 is a schematic flowchart of a method for online detection of synchronous vectors of operating gears of a distribution transformer provided by an embodiment of the present application;

[0054] Figure 2 is a schematic diagram of an online detection circuit for electrical parameters of a distribution transformer provided by an embodiment of the present application;

[0055] Figure 3 is another schematic diagram of an online detection circuit for electrical parameters of a distribution transformer provided by an embodiment of the present application;

[0056] Figure 4This is a schematic structural diagram of an on-line detection device for synchronous vectors of operating positions of a distribution transformer provided by an embodiment of the present application. Detailed implementation manners

[0057] In order to enable those skilled in the art to better understand the solutions of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present application.

[0058] The terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned accompanying drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally further includes steps or units not listed, or optionally further includes other steps or units inherent to these processes, methods, products or devices.

[0059] Referring to "embodiment" herein means that a specific feature, structure or characteristic described in connection with the embodiment can be included in at least one embodiment of the present application. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0060] The embodiments of the present application will be described below with reference to the accompanying drawings in the embodiments of the present application.

[0061] Please refer to Figure 1 , which is a schematic flow chart of a method for on-line detection of synchronous vectors of operating positions of a distribution transformer provided by an embodiment of the present application. As Figure 1 shown, the method includes:

[0062] 101. Obtain the nameplate parameters of the distribution transformer, and calculate the impedance value of the low-voltage side to the high-voltage side of the distribution transformer under each operating position according to the above-mentioned nameplate parameters of the distribution transformer.

[0063] The execution subject of the method in the embodiment of the present application can be an on-line detection device for synchronous vectors of operating positions of a distribution transformer, and in practical applications, it can be implemented based on a circuit system.

[0064] The nameplate parameters of the distribution transformer involved in the embodiments of the present application are the basis for calculating the impedance reference value of the low-voltage side to the high-voltage side at each tap position. Through the nameplate parameters, the theoretical impedance values of the transformer at different tap positions can be accurately calculated, and these impedance reference values are the key reference data for subsequent on-line detection and tap position judgment.

[0065] Specifically, the nameplate parameters may include but are not limited to the following:

[0066] Rated capacity: It is used to calculate the impedance reference value of the transformer and reflects the power transmission capacity of the transformer.

[0067] Rated high-voltage side voltage: The high-voltage side voltage values at different tap positions are used to calculate the impedance at different tap positions.

[0068] Rated low-voltage side voltage: The voltage value of the low-voltage side is used for impedance calculation.

[0069] Percentage of impedance voltage: It reflects the impedance characteristics of the transformer and is a key parameter for calculating the impedance reference value.

[0070] Specifically, the impedance value of the low-voltage side to the high-voltage side of the distribution transformer at each tap position can be calculated according to the following formula:

[0071]

[0072] Where, Z i is the impedance value of the low-voltage side to the high-voltage side of the distribution transformer at tap position i, with the unit of Ω, U e2 is the rated low-voltage side voltage of the distribution transformer, with the unit of kV; U E is the nominal rated voltage of the distribution transformer; U Ei is the rated high-voltage side voltage of the distribution transformer at tap position i, with the unit of kV; S N is the rated capacity of the distribution transformer, with the unit of kVA; U X % is the percentage of impedance voltage of the distribution transformer. For example, when the percentage of impedance voltage of the distribution transformer is 4%, then U X % = 4.

[0073] 102. Synchronously measure the low-voltage side voltage vector, the current vector output by the low-voltage side, and the low-voltage side neutral point voltage vector of the above distribution transformer.

[0074] Among them, the measurement points for synchronous measurement can be at a distance less than a preset distance threshold from the outgoing line end of the distribution transformer. By approaching the outgoing line end of the distribution transformer, the lead length between the measurement point and the sensor is reduced to reduce the error introduced by the lead impedance.

[0075] Specifically, when measuring the voltage vector on the low-voltage side of a distribution transformer, the current vector on the low-voltage side of the distribution transformer, and the neutral point voltage vector on the low-voltage side of the distribution transformer, voltage and current sensors with high-precision amplitude and phase angle measurement can be used. The sensors can be any type of sensor such as electromagnetic sensors, optoelectronic sensors, etc.; the errors (amplitude error and phase error) of the voltage and current sensors meet the requirements of the transformer parameter measurement errors specified by the user.

[0076] 103. When the amplitude of the zero-sequence current on the low-voltage side of the above-mentioned distribution transformer reaches the current detection threshold, or the modulus of the neutral point voltage vector on the low-voltage side reaches the voltage detection threshold, obtain the detection loop and combine the circuit principle and the synchronous voltage vector on the low-voltage side, the synchronous current vector output on the low-voltage side, and the neutral point synchronous voltage vector on the low-voltage side of the above-mentioned distribution transformer to calculate the short-circuit impedance value from the low-voltage side to the high-voltage side.

[0077] In an alternative embodiment, the voltage detection threshold and the current detection threshold can be determined according to the measurement accuracy of the sensor, where the voltage detection threshold is not less than the minimum resolvable voltage measured by the sensor, and the current detection threshold is not less than the minimum resolvable current measured by the sensor.

[0078] In an alternative embodiment, if the amplitude of the zero-sequence current on the low-voltage side of the above-mentioned distribution transformer does not reach the above-mentioned current detection threshold, and the modulus of the neutral point voltage vector on the low-voltage side does not reach the above-mentioned voltage detection threshold, an adjustable impedance is connected to increase the zero-sequence current.

[0079] Further optionally, the above method further includes:

[0080] Compare the moduli of the three-phase voltage vectors on the low-voltage side to obtain the phase with the lowest voltage amplitude on the low-voltage side, and connect the above-mentioned adjustable impedance between the phase with the lowest voltage amplitude on the low-voltage side and the neutral point on the low-voltage side;

[0081] Alternatively, compare the moduli of the three-phase current vectors on the low-voltage side to obtain the phase with the largest current amplitude on the low-voltage side, and connect the above-mentioned adjustable impedance between the phase with the largest current amplitude on the low-voltage side and the neutral point on the low-voltage side.

[0082] Specifically, if the current detection threshold or the voltage detection threshold is not reached, the zero-sequence current can be increased by connecting an adjustable impedance so that the modulus of the neutral point voltage vector on the low-voltage side of the distribution transformer reaches the neutral point voltage detection threshold, or the amplitude of the neutral point current on the low-voltage side of the distribution transformer reaches the current detection threshold. The method for connecting the adjustable impedance can include:

[0083] Compare the magnitudes of the three-phase voltage vectors on the low-voltage side of the distribution transformer to obtain the phase with the lowest voltage magnitude on the low-voltage side of the distribution transformer, and connect an adjustable impedance between the phase with the lowest voltage magnitude on the low-voltage side of the distribution transformer and the neutral point on the low-voltage side of the distribution transformer; or compare the magnitudes of the three-phase current vectors on the low-voltage side of the distribution transformer to obtain the phase with the largest current magnitude on the low-voltage side of the distribution transformer, and connect an adjustable impedance between the phase with the largest current magnitude on the low-voltage side of the distribution transformer and the neutral point on the low-voltage side of the distribution transformer.

[0084] Among them, the above adjustable impedance can be a resistor, a capacitor, an inductor, or any combination thereof.

[0085] In one implementation, the above-mentioned detection loop is obtained, combined with the circuit principle, and the low-voltage side voltage vector, the low-voltage side output current vector, and the low-voltage side neutral point voltage vector of the above-mentioned distribution transformer are used to calculate the short-circuit impedance value of the low-voltage side to the high-voltage side, including:

[0086] When the three-phase voltage vector, three-phase current vector, and neutral point voltage vector of the low-voltage side of the above-mentioned distribution transformer are obtained, the following formula is used to calculate the short-circuit impedance value of the low-voltage side to the high-voltage side:

[0087]

[0088] When the zero-sequence voltage vector, three-phase current vector, and neutral point voltage vector of the low-voltage side of the above-mentioned distribution transformer are obtained, the following formula is used to calculate the short-circuit impedance value of the low-voltage side to the high-voltage side:

[0089]

[0090] When the zero-sequence voltage vector, zero-sequence current vector, and neutral point voltage vector of the low-voltage side of the above-mentioned distribution transformer are obtained, the following formula is used to calculate the short-circuit impedance value of the low-voltage side to the high-voltage side:

[0091]

[0092] When the three-phase voltage vector, zero-sequence current vector, and neutral point voltage vector of the low-voltage side of the above-mentioned distribution transformer are obtained, the following formula is used to calculate the short-circuit impedance value of the low-voltage side to the high-voltage side:

[0093]

[0094] Among them, are the three-phase voltage vectors on the low-voltage side of the above-mentioned distribution transformer respectively; are the three-phase current vectors output on the low-voltage side of the above-mentioned distribution transformer respectively; Z 21 is the short-circuit impedance of the low-voltage side of the above-mentioned distribution transformer to the high-voltage side, is the neutral point voltage vector on the low-voltage side of the above-mentioned distribution transformer; UL0 is the zero-sequence voltage measured at the low-voltage side of the above distribution transformer, is the zero-sequence current measured at the low-voltage side of the distribution transformer; mod() is the modulo function.

[0095] 104. Calculate the difference between the short-circuit impedance modulus from the low-voltage side to the high-voltage side and the impedance value from the low-voltage side to the high-voltage side at each tap of the above distribution transformer to obtain the absolute value of the impedance difference at each tap.

[0096] 105. Determine that the tap corresponding to the minimum absolute value of the impedance differences at the above taps is the current operating tap of the above distribution transformer.

[0097] The method in the embodiments of the present application can detect the operating tap of the transformer under the operating state of the transformer, complete the tap verification without power outage, reduce the power outage time and economic losses, and avoid voltage fluctuations caused by incorrect taps. It can give early warnings of mechanical jamming or electrical connection failures, avoid equipment damage, provide real-time data support for the automatic dispatching of the power grid, and assist in dynamic voltage regulation and load optimization. The present invention provides strong support for the stable power supply of distribution transformers and the construction of smart grids, provides a solution for the digital twin of transformers, and supports the digital transformation of the power system.

[0098] The following explains the impedance calculation formula from the low-voltage side to the high-voltage side of the distribution transformer mentioned in the embodiments of the present application.

[0099] Figure 2 is a schematic diagram of an on-line detection circuit for electrical parameters of a distribution transformer provided by an embodiment of the present application. Figure 2 is an equivalent circuit diagram of a three-phase transformer for analyzing and calculating the impedance of the transformer. In this equivalent circuit, each phase of the transformer is represented as a voltage source (-E 21 ) with an exciting reactance (Z A , -E B , -E C ), and these voltage sources represent the electromotive forces on the high-voltage side of the transformer. Z OH represents the external circuit impedance of the transformer, while Z a , Z b , Z c represent the equivalent impedance from the low-voltage side to the high-voltage side of the transformer.

[0100] Specifically, are the three-phase power supplies on the low-voltage side of the distribution transformer respectively; are the three-phase voltage vectors on the low-voltage side of the distribution transformer obtained by synchronous measurement respectively; are the three-phase current vectors output from the low-voltage side of the distribution transformer obtained by synchronous measurement respectively; is the neutral-point voltage vector on the low-voltage side of the distribution transformer obtained by synchronous measurement; Z 21It is the short-circuit impedance (including short-circuit resistance and short-circuit reactance) of the low-voltage side of the distribution transformer to the high-voltage side. According to Kirchhoff's theorem, it can be known that:

[0101]

[0102] Adding the three equations gives:

[0103]

[0104] Since It can be obtained that:

[0105]

[0106] Therefore:

[0107]

[0108] There are many series of distribution transformers. For example, S9, S9-M, S10-M, and S11-M series enclosed oil-immersed transformers; SCB8, SC(B)9, and SCR-10 series encapsulated coil dry-type transformers. In one implementation, an S11-M-200 / 10 type distribution transformer is optionally selected to set up the transformer simulation model, and this solution is applicable to any other series of distribution transformers. The capacity is set to 200 kVA, and the connection group is Dyn11. The rated voltages of each gear on the high-voltage side are 9.5 kV for gear 1, 10 kV for gear 2, and 10.5 kV for gear 3 respectively, the rated voltage on the low-voltage side is 0.4 kV, the short-circuit impedance of the transformer is set to 4%, and the load loss of the transformer is set to 2.6 kW. Accordingly, the impedance values of the low-voltage side to the high-voltage side at each gear of the distribution transformer are calculated to be 0.0304 for gear 1, 0.032 Ω for gear 2, and 0.0336 Ω for gear 3. It can be referred to Figure 1 , according to Figure 1 the schematic diagram of the implementation process shown, the above transformer simulation model is used for simulation, and the example is as follows:

[0109] Execute step 101, and the impedance values of the low-voltage side to the high-voltage side at each gear of the distribution transformer can be calculated to be: 0.0304 for gear 1, 0.032 Ω for gear 2, and 0.0336 Ω for gear 3.

[0110] Step 102 is executed, and the three-phase voltage vectors on the low-voltage side of the distribution transformer can be synchronously measured as 103.26 - i196.15 V, -242.03 + i4.34 V, 104.71 + i203.38 V respectively, and the three-phase current vectors output on the low-voltage side of the distribution transformer are 12.9 - i24.51 A, -12.1 + i0.22 A, 10.48 + i20.36 A respectively; the neutral point voltage vector on the low-voltage side of the distribution transformer is -11.32 + i3.98 V, and its modulus is 12 V. At the same time, the neutral point current on the low-voltage side of the distribution transformer is measured as 11.95 A (effective value).

[0111] Figure 3 Another schematic diagram of the on-line detection circuit for the electrical parameters of the distribution transformer provided by the embodiment of the present application. This circuit is used to detect and calculate the operating parameters of the distribution transformer in real time, such as voltage, current, impedance, etc., to ensure the safe and stable operation of the transformer. The following is a detailed description of Figure 3 each part in

[0112] Voltage transformer (PT): Marked as 1, it is used to measure the voltage on the high-voltage side of the transformer. The voltage transformer converts high voltage into low voltage for easy measurement and protection of equipment.

[0113] Current transformer (CT): Marked as 2, it is used to measure the current on the high-voltage side of the transformer. The current transformer also converts large current into small current for easy measurement and protection of equipment.

[0114] Low-voltage side voltage measurement: Marked as 3, this part may include voltage measurement equipment directly connected to the low-voltage side of the transformer to detect the voltage on the low-voltage side.

[0115] Tap changer: Marked as 4, it is used to adjust the tap of the transformer, thereby changing the voltage ratio of the transformer. By changing the tap, the output voltage of the transformer can be adjusted to adapt to load changes.

[0116] Adjustable impedance unit: Marked as 5, it is used to appropriately adjust the unbalance degree of the load of the distribution transformer. This may include resistors, capacitors, inductors or combinations thereof, which are used to simulate loads or adjust circuit characteristics.

[0117] Phase-splitting switching switch: Marked as 6, it is connected between the low-voltage side of the distribution transformer and the adjustable impedance unit, and is used to connect the adjustable impedance between the phase with the lowest voltage on the low-voltage side of the distribution transformer and the ground. This helps to balance the loads of each phase and reduce the unbalanced current.

[0118] Grounding: The entire detection circuit needs to be safely grounded to prevent electrical faults and protect the safety of operators.

[0119] Control and calculation unit: Marked as 7, usually located at the bottom or nearby of the detection device, responsible for collecting data from voltage transformers, current transformers and low-voltage side voltage measurement devices, and performing processing and calculations. This unit may include a data acquisition system, a microprocessor or other computing devices for performing the following functions:

[0120] Calculating the impedance of the transformer, detecting the operating state of the transformer, providing real-time data to the power grid automation dispatching system, issuing an alarm when an abnormal situation is detected, etc.

[0121] The design purpose of the entire on-line detection loop is to detect the electrical parameters of the transformer in real time during its operation, so as to timely discover and handle potential problems, thereby improving the reliability and efficiency of the power grid.

[0122] Based on Figure 3 the detection loop, by performing step 103, the impedance calculation formula of the low-voltage side of the distribution transformer to the high-voltage side can be obtained as:

[0123]

[0124] where are the three-phase voltage vectors of the low-voltage side of the distribution transformer respectively; are the three-phase current vectors output from the low-voltage side of the distribution transformer respectively; Z 21 is the short-circuit impedance (including short-circuit resistance and short-circuit reactance) of the low-voltage side of the distribution transformer to the high-voltage side, is the neutral point voltage vector of the low-voltage side of the distribution transformer. The short-circuit impedance value of the low-voltage side of the distribution transformer to the high-voltage side can be calculated to be 0.032 Ω.

[0125] Furthermore, by performing step 104, the absolute values of the impedance differences of each gear obtained by calculating the difference between the modulus value of the short-circuit impedance of the low-voltage side of the distribution transformer to the high-voltage side and the impedance value of the low-voltage side of the distribution transformer to the high-voltage side at each gear obtained above are respectively: 0.0016 Ω for gear 1, 0 Ω for gear 2, and 0.0016 Ω for gear 3.

[0126] By performing step 105, it can be determined that the gear corresponding to the minimum value of the absolute value of the impedance difference of each gear is the current operating gear of the distribution transformer, that is, gear 2.

[0127] Based on the description of the foregoing method embodiments, the embodiments of the present application further provide an on-line detection device for synchronizing vectors of the operating gears of a distribution transformer.

[0128] Figure 4 is a schematic structural diagram of an on-line detection device for synchronizing vectors of the operating gears of a distribution transformer provided by an embodiment of the present application.

[0129] As Figure 4As shown, the on-line detection device 400 for the synchronous vector of the operating position of the distribution transformer includes:

[0130] A neutral point voltage measurement unit 410, connected between the neutral point of the low-voltage side of the distribution transformer and the ground, for measuring the neutral point voltage vector of the low-voltage side of the above-mentioned distribution transformer;

[0131] A neutral point current measurement unit 420, connected between the neutral point of the low-voltage side of the above-mentioned distribution transformer and the ground, for measuring the neutral point current of the low-voltage side of the above-mentioned distribution transformer;

[0132] A voltage measurement unit 430, connected to the low-voltage side of the above-mentioned distribution transformer, for measuring the low-voltage side voltage vector;

[0133] A current measurement unit 440, connected to the low-voltage side of the above-mentioned distribution transformer, for measuring the current vector output by the low-voltage side;

[0134] A phase-separated switching switch 450, connected between the low-voltage side of the above-mentioned distribution transformer and the adjustable impedance unit, for connecting the above-mentioned adjustable impedance unit between the phase with the lowest low-voltage side voltage and the ground;

[0135] The above-mentioned adjustable impedance unit 460, connected to the low-voltage side of the above-mentioned distribution transformer, for adjusting the unbalance degree of the load of the above-mentioned distribution transformer;

[0136] A control and calculation unit 470, connected to the above-mentioned neutral point voltage measurement unit 410, the above-mentioned neutral point current measurement unit 420, the above-mentioned voltage measurement unit 430, the above-mentioned current measurement unit 440, the phase-separated switching switch 450, and the above-mentioned adjustable impedance unit 460, for:

[0137] Obtaining the impedance reference value of the low-voltage side to the high-voltage side of the above-mentioned distribution transformer at each operating position;

[0138] Calculating the short-circuit impedance value of the low-voltage side to the high-voltage side;

[0139] Calculating the difference between the short-circuit impedance modulus value of the low-voltage side to the high-voltage side and the impedance value of the low-voltage side to the high-voltage side of the above-mentioned distribution transformer at each operating position, and obtaining the absolute value of the impedance difference at each operating position;

[0140] Determining that the operating position corresponding to the minimum value of the absolute value of the impedance difference at each operating position is the current operating position of the above-mentioned distribution transformer.

[0141] It can be understood that the relevant content of each module involved in Figure 4 has been described in detail in the foregoing method embodiments, and specifically, reference can be made to the content in the method embodiments; that is Figure 4 The provided on-line detection device 400 for the synchronous vector of the operating position of the distribution transformer can execute as Figure 1Any steps in the illustrated embodiments are not elaborated herein.

[0142] In one embodiment, the structure of the above-mentioned on-line detection device 400 for the synchronous vector of the operating gear of the distribution transformer may partially correspond to Figure 3 the detection circuit shown, which is not elaborated herein.

[0143] Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be completed by instructing relevant hardware through a computer program. The program can be stored in a non-volatile computer-readable storage medium. When the program is executed, it may include the processes of the embodiments of the above methods. Among them, any reference to a memory, storage, database, or other medium used in the various embodiments provided in the present application may include non-volatile and / or volatile memories. Non-volatile memories may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memories may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and Rambus dynamic RAM (RDRAM), etc.

[0144] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0145] The above-described embodiments merely represent several implementation manners of the present application. The description thereof is relatively specific and detailed, but it should not be construed as a limitation on the patent scope of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. An online detection method for synchronous vectors of operating positions of a distribution transformer, characterized in that Including: Obtain the nameplate parameters of the distribution transformer, and calculate the impedance value of the low-voltage side to the high-voltage side at each tap of the distribution transformer according to the nameplate parameters of the distribution transformer; Synchronously measure the low-voltage side voltage vector, the current vector output by the low-voltage side, and the low-voltage side neutral point voltage vector of the distribution transformer; When the amplitude of the zero-sequence current on the low-voltage side of the distribution transformer reaches the current detection threshold, or the modulus of the low-voltage side neutral point voltage vector reaches the voltage detection threshold, obtain the detection circuit and combine the circuit principle and the low-voltage side synchronous voltage vector, the low-voltage side output synchronous current vector, and the low-voltage side neutral point synchronous voltage vector of the distribution transformer to calculate the short-circuit impedance value of the low-voltage side to the high-voltage side; Calculate the difference between the short-circuit impedance modulus of the low-voltage side to the high-voltage side and the impedance value of the low-voltage side to the high-voltage side at each tap of the distribution transformer to obtain the absolute value of the impedance difference at each tap; Determine that the tap corresponding to the minimum value of the absolute value of the impedance difference at each tap is the current operating tap of the distribution transformer.

2. The on-line detection method for synchronous vectors of operating positions of a distribution transformer according to claim 1, wherein The calculating the impedance value of the low-voltage side to the high-voltage side at each tap of the distribution transformer according to the nameplate parameters of the distribution transformer includes: Calculating the impedance value of the low-voltage side to the high-voltage side at each tap of the distribution transformer according to the following formula: Among them, Z i is the impedance value of the low-voltage side to the high-voltage side of the distribution transformer at tap position i, with the unit of Ω, U e2 is the rated voltage of the low-voltage side of the distribution transformer, with the unit of kV; U E is the nominal rated voltage of the distribution transformer; U Ei is the rated voltage of the high-voltage side of the distribution transformer at tap position i, with the unit of kV; S N is the rated capacity of the distribution transformer, with the unit of kVA; U X % is the percentage of the impedance voltage of the distribution transformer.

3. The on-line detection method for synchronous vectors of the operating gear positions of a distribution transformer according to claim 2, wherein The impedance value of the low-voltage side to the high-voltage side at each tap of the distribution transformer is obtained by measuring the short-circuit impedance test of the high-voltage winding to the low-voltage winding at each tap when the distribution transformer leaves the factory or directly measuring the short-circuit impedance of the low-voltage winding to the high-voltage winding.

4. The on-line detection method for synchronous vectors of operating positions of a distribution transformer according to claim 1, characterized in that The measuring points of the synchronous measurement are less than a preset distance threshold from the outgoing line end of the distribution transformer.

5. The on-line detection method for synchronous vectors of the operating gear of a distribution transformer according to claim 1, characterized in that, The method further includes: When synchronously measuring the low-voltage side voltage vector, the current vector output by the low-voltage side, and the low-voltage side neutral point voltage vector of the distribution transformer, use voltage and current sensors with high-precision measurement of amplitude and phase angle.

6. The on-line detection method for synchronous vectors of operating gears of a distribution transformer according to claim 1, wherein The voltage detection threshold and the current detection threshold are determined according to the measurement accuracy of the sensor. The voltage detection threshold is not less than the minimum resolution voltage for the sensor to ensure accurate measurement, and the current detection threshold is not less than the minimum resolution current for the sensor to ensure accurate measurement.

7. The on-line detection method for synchronous vectors of operating positions of a distribution transformer according to claim 6, characterized in that, If the amplitude of the zero-sequence current on the low-voltage side of the distribution transformer does not reach the current detection threshold, and the modulus of the low-voltage side neutral point voltage vector does not reach the voltage detection threshold, connect an adjustable impedance to increase the zero-sequence current.

8. The on-line detection method for synchronous vectors of operating positions of a distribution transformer according to claim 7, characterized in that The method further includes: Compare the moduli of the low-voltage side three-phase voltage vectors to obtain the phase with the lowest low-voltage side voltage amplitude, and connect the adjustable impedance between the phase with the lowest low-voltage side voltage amplitude and the low-voltage side neutral point; Or, compare the moduli of the low-voltage side three-phase current vectors to obtain the phase with the largest low-voltage side current amplitude, and connect the adjustable impedance between the phase with the largest low-voltage side current amplitude and the low-voltage side neutral point.

9. The on-line detection method for synchronous vectors of operating gears of a distribution transformer according to claim 8, characterized in that, The adjustable impedance uses a resistor, a capacitor, an inductor, or any combination thereof.

10. The on-line detection method for synchronous vectors of the operating positions of a distribution transformer according to claim 1, characterized in that, The obtaining the detection circuit and combining the circuit principle and the low-voltage side synchronous voltage vector, the low-voltage side output synchronous current vector, and the low-voltage side synchronous neutral point voltage vector of the distribution transformer to calculate the short-circuit impedance value of the low-voltage side to the high-voltage side includes: When the low-voltage side synchronous three-phase voltage vector, synchronous three-phase current vector, and neutral point synchronous voltage vector of the distribution transformer are obtained, the short-circuit impedance value of the low-voltage side to the high-voltage side is calculated using the following formula: When the low-voltage side synchronous zero-sequence voltage vector, synchronous three-phase current vector, and neutral point synchronous voltage vector of the distribution transformer are obtained, the short-circuit impedance value of the low-voltage side to the high-voltage side is calculated using the following formula: When the low-voltage side synchronous zero-sequence voltage vector, synchronous zero-sequence current vector, and neutral point synchronous voltage vector of the distribution transformer are obtained, the short-circuit impedance value of the low-voltage side to the high-voltage side is calculated using the following formula: When the low-voltage side synchronous three-phase voltage vector, synchronous zero-sequence current vector, and neutral point synchronous voltage vector of the distribution transformer are obtained, the short-circuit impedance value of the low-voltage side to the high-voltage side is calculated using the following formula: Among them, are respectively the three-phase voltage vectors of the low-voltage side of the distribution transformer; are respectively the three-phase current vectors output from the low-voltage side of the distribution transformer; Z 21 is the short-circuit impedance of the low-voltage side of the distribution transformer to the high-voltage side, is the neutral-point voltage vector of the low-voltage side of the distribution transformer; U L0 is the zero-sequence voltage measured on the low-voltage side of the distribution transformer, is the zero-sequence current measured on the low-voltage side of the distribution transformer.

11. An on-line detection device for synchronous vectors of operating gears of a distribution transformer, characterized in that, Including: A neutral point voltage measurement unit, connected between the neutral point of the low-voltage side of the distribution transformer and the ground, for measuring the neutral point voltage vector of the low-voltage side of the distribution transformer; A neutral point current measurement unit, connected between the neutral point of the low-voltage side of the distribution transformer and the ground, for measuring the neutral point current of the low-voltage side of the distribution transformer; A voltage measurement unit, connected to the low-voltage side of the distribution transformer, for measuring the low-voltage side voltage vector; A current measurement unit, connected to the low-voltage side of the distribution transformer, for measuring the current vector output by the low-voltage side; A phase-splitting switching switch, connected between the low-voltage side of the distribution transformer and the adjustable impedance unit, for connecting the adjustable impedance unit between the phase with the lowest low-voltage side voltage and the ground; The adjustable impedance unit, connected to the low-voltage side of the distribution transformer, for adjusting the unbalance degree of the load of the distribution transformer; A control calculation unit, connected to the voltage measurement unit, the current measurement unit, the neutral point voltage measurement unit, the adjustable impedance unit, and the phase-splitting switching switch, for: Obtaining the impedance reference value of the low-voltage side to the high-voltage side of the distribution transformer at each tap position; Calculating the short-circuit impedance value of the low-voltage side to the high-voltage side; Calculating the difference between the short-circuit impedance modulus value of the low-voltage side to the high-voltage side and the impedance value of the low-voltage side to the high-voltage side at each tap position of the distribution transformer, and obtaining the absolute value of the impedance difference at each tap position; Determining that the tap position corresponding to the minimum value of the absolute value of the impedance difference at each tap position is the current operating tap position of the distribution transformer.

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