Autotransformer wiring group verification method and device, electronic equipment and medium

Abstract

The invention discloses an autotransformer wiring group verification method and device, electronic equipment and a medium, and relates to the technical field of power grid control, and the method comprises the steps: analyzing the short-circuit operation condition of a main transformer, and drawing a hexagonal diagram to analyze the CT polarity and the wiring group of the main transformer; the short-circuit voltage of the transformer is added to the medium-voltage side, so that the high-voltage side and the low-voltage side are short-circuited, and the three-phase current of a secondary winding of the transformer is detected; one phase voltage is cut off, the main transformer generates zero-sequence current, and an N line of a secondary winding of the transformer is checked to obtain a main transformer connection group; opening two short-circuited sides of the transformer, and detecting the voltage transformation ratio of the transformer; and comparing and checking the three-phase current / main transformer connection group and the voltage transformation ratio with a transformer calibration value. The method is not affected by the operation environment of a transformer substation, the polarity, the transformation ratio and the connection group of the self-coupling transformer bushing current transformer can be completely checked, and meanwhile main transformer protection differential loop verification is met. Operation is simple, and installation is convenient.

Description

Technical Field

[0001] The present invention relates to the technical field of transformer substation engineering construction, and in particular to a method, a device, an electronic device and a medium for checking autotransformer connection groups in transformer substation installation and commissioning construction. Background Art

[0002] In the construction of new or expanded substations, the installation and commissioning of multiple main transformers will be involved, and the differential current circuit and wiring group of the main transformer are the key inspection items. The main protection of the transformer is divided into differential protection and gas protection. The differential protection of 500kV autotransformer includes conventional ratio differential, zero-sequence differential, side differential, and phase differential protection. The current position collected by each function is different.

[0003] Traditional inspection methods have certain limitations and incompleteness. Traditional polarity testing requires batteries of a certain capacity and many test wires. In addition, in the expansion and reconstruction of the station, the primary conductor of the main transformer bushing is rarely removed after installation due to cross-operation. Otherwise, a crane is required and personnel work at high altitude, which poses operational risks and increases labor intensity. If the primary conductor of the main transformer bushing is connected, since it is an operating substation, strong induction electricity will interfere with the polarity inspection of the main transformer bushing CT. The test personnel need to go to the main transformer bushing wiring board for test wiring, which poses a risk of high-altitude operation. This results in a long measurement time and fatigue for the test personnel. Conventional current riser instruments are bulky, the insulating rod is too long, the current riser wire is too long and too heavy, and the assembly takes a long time, which greatly increases the workload of the test personnel and is time-consuming and laborious. If the point polarity method is used for the main transformer bushing, it is also necessary to climb to the bushing head for wiring, which increases the danger of working at height. Under normal conditions, on-site relay protection personnel cannot perform a bushing CT ratio check after the main transformer is installed. The common main transformer winding connection method in large grounding systems is the YD11 connection method. Especially for the 500kV autotransformer low-voltage side winding triangle connection method, it is a difficult problem to check it after on-site assembly.

[0004] Guangxi Power Grid's 500kV Yongzhou substation once had an accident in which a bushing CT of the newly installed #1 main transformer had an open circuit in the secondary junction box without being checked. As a result, after a period of operation, the open secondary winding generated high voltage, which burned the insulation layer of the bushing CT and caused a serious accident of oil leakage from the main transformer bushing riser. Since the equipment was from different manufacturers, the factory designs of the beginning and end of the bushing on the low-voltage side of the main transformer were inconsistent. In the expansion projects of the main transformer of the Jiangmen 500kV Aofeng substation and the Beihai 500kV Fucheng substation, the test personnel found through the nameplate that the beginning and end of the bushing on the low-voltage side were opposite to the design drawing. After verification, the design was redrawn and the triangle connection was reconnected on site.

[0005] During the protection renovation of the 500kV main transformer of a 500kV substation in Guangdong, after the startup, the second set of main transformer phase differential protection was activated during operation, tripping the three sides of the main transformer. Since the second set of main transformer protection is provided by Beijing Sifang Company, the main transformer protection of Beijing Sifang Company has a unique function of phase differential protection, which uses the bushing current on the low-voltage side of the main transformer; when using the head end current, P1 is required to point to the sky, and when using the tail end bushing current, P1 is required to point to the transformer body. The bushing P1 on the low-voltage side of the station all points to the sky, and the acceptance personnel and commissioning personnel did not pay attention to the polarity requirements of this function. When the second set of main transformer protection used the tail end bushing current, it was wired in the positive extraction mode according to the design drawing, resulting in the wrong polarity of the phase differential current circuit; during the commissioning process, due to the low load, the protection action value could not be reached. After the commissioning, as the load increased, the differential current action value was reached, causing the protection action.

[0006] Taking the main transformer protection of Beijing Sifang Company as an example, the main transformer protection stipulates that the switch CT on each side of the transformer has the side far away from the transformer (the bus side of this phase) as the positive polarity end; the bushing CT installed at the beginning of the winding on each side has the side far away from the transformer (the bus side of this phase) as the positive polarity end, and the bushing CT installed at the end of the winding on each side has the side close to the transformer (the bus side of this phase) as the positive polarity end. The polarity of the zero-sequence CT of the common winding has the side far away from the transformer as the positive polarity end. The following figure shows the CT polarity of one phase in the phase-splitting transformer. There is an inconsistency between the design structure of the main transformer and the polarity required by the protection equipment. Since it is impossible to meet the primary current on each side of the main transformer at the same time, the main transformer is simulated to operate with load, and the polarity of the primary equipment of the main transformer and the polarity of the secondary protection device are fully checked and judged to determine the correctness of the coordination.

[0007] The application number in the prior art is CN201910620896, and its name is a method and device for analyzing and recording the closing and unclosing process of distribution lines. The method for analyzing and recording the closing and unclosing process of distribution lines provided by the invention can quickly and effectively analyze the electrical quantity information required for the closing and unclosing operation by constructing a loop model, performing consistency check on the main transformer wiring group, checking the data before closing the loop, monitoring the closing and unclosing process, and analyzing and recording the data after closing and unclosing the loop. It can also perform safety checks before closing and unclosing operations, monitor data during closing and unclosing, and record historical records after closing and unclosing, thereby reducing the operation of dispatching personnel, providing auxiliary decision-making, and providing historical measured data support for the calculation of closing and unclosing impact current. It solves the problem of checking the consistency of the main transformer wiring group during the closing and unclosing process. It cannot meet the inspection before operation and is not suitable for use in the commissioning and construction stage of substations.

[0008] The application number is CN201911368016 and its name is a kind of autotransformer zero-sequence differential protection verification device and its verification method. Through the central processing unit of the detected high, medium and low voltage side current data, the display unit that displays the detected high, medium and low voltage side current data to the staff in a dynamic curve chart, and the editing unit that edits and inputs the corresponding control instructions and imports the model, the current data of the high voltage end, medium voltage end and low voltage end of the autotransformer are respectively verified and detected. When protecting and verifying the internal circuit of the autotransformer, according to the current data of the high voltage side, medium voltage side and low voltage side in the autotransformer circuit, the verification processing is respectively made accordingly to improve the accuracy of the verification data. This method improves the accuracy and efficiency of the zero-sequence differential protection verification of the autotransformer, but cannot completely check the external circuit of the autotransformer main transformer protection device, such as the polarity, transformation ratio and connection group of the bushing current transformer. There are certain limitations and incompleteness.

[0009] At present, the existing technologies cannot completely check the polarity, ratio and connection group of the bushing current transformer and the low-voltage side of the autotransformer, and cannot completely guarantee the reliability and correctness of the circuit; and because the instruments and equipment are bulky and require the cooperation of many people, the work efficiency is not high. It is necessary to develop a method for checking the connection group and differential circuit of the autotransformer. Summary of the invention

[0010] The technical problem to be solved by the present invention is to solve the deficiencies in the prior art and to design a method for verifying the connection group of an autotransformer, which is not affected by the operating environment of the substation and can completely check the polarity, transformation ratio and connection group of the autotransformer bushing current transformer, while meeting the verification of the differential circuit of the main transformer protection.

[0011] The technical solution adopted by the present invention to solve the technical problem is:

[0012] In a first aspect, the present invention provides a method for verifying autotransformer connection groups, comprising:

[0013] Analyze the short-circuit operation of the main transformer and draw a hexagonal diagram to analyze the CT polarity and main transformer wiring group;

[0014] Add the short-circuit voltage of the transformer to the medium-voltage side, so that the high-voltage side and the low-voltage side are short-circuited, and detect the three-phase current of the secondary winding of the transformer;

[0015] Disconnect one of the phase voltages to allow the main transformer to generate zero-sequence current, and check the N line of the secondary winding of the transformer to obtain the main transformer connection group;

[0016] Open both sides of the short circuit of the transformer and detect the voltage transformation ratio of the transformer;

[0017] Compare and verify the three-phase current / main transformer connection group and voltage ratio with the transformer calibration value.

[0018] As a further technical solution of the present invention, the analysis of the short-circuit operation of the main transformer and the drawing of a hexagonal diagram to analyze the CT polarity and the main transformer connection group specifically include:

[0019] When the main transformer is in short-circuit operation, it is equivalent to an inductor element. With the line voltage as a fixed reference, the primary polarity terminal P1 of the high-resistance line-side bushing CT is pointed to the sky, the secondary is positively drawn, and the secondary current flows out from the same-name terminal S1. At this time, the angle measured is that the voltage leads the secondary current of the line-side CT by 90°;

[0020] Add positive sequence to the three-phase AC mains on the medium voltage side and make a theoretical vector diagram of phase A;

[0021] Take U 中A Fixed as the reference voltage phasor, rotating counterclockwise to U 中A The angle between 中A The angle of the leading current; at this time, it can be known that the inductive transformer U 中A Ahead I 中 The angle is 90°, and the secondary current at the a-end of the high side, common side, and low voltage side is proportional to I 中 The angle difference is 180°; I 中 The vector magnitude is I 高 with I 公 Sum of amplitudes, opposite angles, I 高 with I 公 The angles of I are all 270°; 低开关 The angle is 240°; 低绕组a The angle is 270°; 低绕组x It is the non-polarity end of the primary winding on the low voltage side, and its angle is opposite to the polarity end CT, so I 低绕组x The angle is 90°;

[0022] By carrying out the primary current flow test of the main transformer as mentioned above and measuring the amplitude and phase of the secondary current of the bushings on each side of the main transformer, the polarity and transformation ratio of the bushing current transformer can be determined.

[0023] The short-circuit voltage of the transformer is added to the medium-voltage side to short-circuit the high-voltage side and the low-voltage side, and the three-phase current of the secondary winding of the transformer is detected; specifically including:

[0024] The short-circuit voltage percentage Vs% given on the transformer nameplate is the percentage of the voltage drop generated on the impedance when the transformer passes the rated current. For large-capacity transformers, the short-circuit reactance Vx% = Vs%, simulating a short-circuit current generated by a main transformer short circuit.

[0025] Calculation of short-circuit impedance voltage on each side:

[0026]

[0027] Among them: V1%, V2%, V3% are the percentages of short-circuit voltage on the high, middle and low sides of the main transformer respectively;

[0028] V 1-2 %、V 2-3 %、V 1-3 % are the percentages of the short-circuit voltages of high to medium, medium to low, and high to low of the main transformer as provided on the manufacturer's nameplate;

[0029] Calculation of equivalent reactance on each side converted to the medium voltage side: (the following are all single-phase calculations)

[0030]

[0031] Among them: X1, X2, and X3 are the equivalent reactances of the high, middle, and low sides of the main transformer respectively;

[0032] VN: voltage value of the medium voltage side of the main transformer at this gear, in kV;

[0033] S N : Rated capacity of main transformer, unit KVA;

[0034] Add a three-phase symmetrical 220V AC voltage to the medium voltage side and calculate the current on each side:

[0035]

[0036] I3′=I2-I1′

[0037] I2 is the actual value on the medium voltage side, I1′ is the per-unit value on the high voltage side, and I3′ is the per-unit value on the low voltage side. The per-unit value needs to be converted to the corresponding voltage level side to obtain the current generated by the actual value on each side.

[0038] As a further technical solution of the present invention, the short-circuit voltage of the transformer is added to the medium voltage side to short-circuit the high voltage side and the low voltage side, and the three-phase current of the secondary winding of the transformer is detected; specifically including:

[0039] A balanced 380V voltage is added to the medium voltage side of the main transformer, and currents of equal amplitude and positive angle sequence of a certain magnitude are obtained in the three phases of the secondary winding of each CT.

[0040] As a further technical solution of the present invention, disconnecting one phase voltage to allow the main transformer to generate zero-sequence current, and checking the N line of the secondary winding of the transformer to obtain the main transformer connection group; specifically including:

[0041] By checking whether the differential current sampling value is zero, even if the collected current value is small, when the polarity is used incorrectly, the current superposition differential current value is obvious; it can be determined that the polarity of the primary equipment of the main transformer and the polarity of the secondary protection device are incorrectly matched; by measuring the phase difference between the low-voltage bushing CT current and the CT current at the low-voltage side switch, the main transformer connection group can be determined.

[0042] As a further technical solution of the present invention, the voltage of one phase is disconnected to allow the main transformer to generate zero-sequence current and the N line of the secondary winding of the transformer is checked; and further comprising:

[0043] Keep one phase voltage disconnected to detect the unbalance of the open triangle voltage.

[0044] As a further technical solution of the present invention, the two sides of the short circuit of the transformer are opened to detect the voltage transformation ratio of the transformer, which specifically includes:

[0045] Open the short-circuited sides of the transformer, detect the voltage transformation ratio of the transformer, measure the PT secondary voltage on the high voltage side / medium voltage side / low voltage side, and verify the correctness of the open delta connection.

[0046] In a second aspect, the present invention also provides an autotransformer connection group verification device, comprising:

[0047] Theoretical analysis module analyzes the short-circuit operation of the main transformer and draws a hexagonal diagram to analyze the CT polarity and main transformer wiring group;

[0048] The current detection module adds the short-circuit voltage of the transformer to the medium-voltage side, causing the high-voltage side and the low-voltage side to be short-circuited, and detects the three-phase current of the secondary winding of the transformer;

[0049] The connection group detection module disconnects one of the phase voltages to allow the main transformer to generate zero-sequence current, and checks the N line of the secondary winding of the transformer to obtain the connection group of the main transformer;

[0050] The voltage transformation ratio detection module opens the short-circuited sides of the transformer to detect the voltage transformation ratio of the transformer;

[0051] The verification and analysis module compares and verifies the three-phase current / main transformer connection group and voltage ratio with the transformer calibration value.

[0052] In a third aspect, the present invention further provides an electronic device comprising a processor, a memory, and a computer program stored in the memory and executable on the processor, wherein the computer program, when executed by the processor, implements the steps of the method for verifying the connection groups of multiple autotransformers as described in any one of claims 7 to 8.

[0053] In a fourth aspect, the present invention further provides a computer-readable storage medium, characterized in that a computer program is stored in the storage medium, and when the computer program is executed by a processor, the following process is implemented:

[0054] Analyze the short-circuit operation of the main transformer and draw a hexagonal diagram to analyze the CT polarity and main transformer wiring group;

[0055] Add the short-circuit voltage of the transformer to the medium-voltage side, so that the high-voltage side and the low-voltage side are short-circuited, and detect the three-phase current of the secondary winding of the transformer;

[0056] Disconnect one of the phase voltages to allow the main transformer to generate zero-sequence current, and check the N line of the secondary winding of the transformer to obtain the main transformer connection group;

[0057] Open both sides of the short circuit of the transformer and detect the voltage transformation ratio of the transformer;

[0058] Compare and verify the three-phase current / main transformer connection group and voltage ratio with the transformer calibration value.

[0059] Compared with the prior art, the present invention has the following beneficial effects:

[0060] The present invention is not affected by the substation operating environment, and can completely check the polarity, ratio and connection group of the autotransformer bushing current transformer, while meeting the main transformer protection differential circuit verification. The operation method is required to be simple and the installation is convenient. The test wire can withstand a long-term large current. The voltage source can be quickly installed on the transformer drainage wire using a grounding insulating rod. The short-circuit impedance of the transformer is used in conjunction with the addition of an AC 380V voltage to generate a short-circuit current in the main transformer to check the correctness of the main transformer differential circuit, the bushing current transformer polarity, ratio and connection group, and solve the problems in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 This is a flow chart of the autotransformer wiring group verification method proposed by the present invention;

[0062] Figure 2 The hexagonal diagram proposed by the present invention for analyzing CT polarity and main transformer wiring groups;

[0063] Figure 3 The equivalent circuit diagram proposed by the present invention;

[0064] Figure 4 The structure diagram of the autotransformer proposed by the present invention;

[0065] Figure 5 This is a structural diagram of an online verification device for relay protection settings proposed by the present invention. DETAILED DESCRIPTION

[0066] The specific implementation of the present invention is described below in conjunction with the accompanying drawings and embodiments:

[0067] It should be noted that the structures, colors, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification so that people familiar with this technology can understand and read them, and are not used to limit the conditions under which the present invention can be implemented. Any structural modification, change in proportional relationship or adjustment of size should still fall within the scope of the technical contents disclosed in the present invention without affecting the effects and purposes that can be achieved by the present invention.

[0068] Embodiment 1

[0069] like Figure 1 As shown, the present invention provides a method for checking the connection group of an autotransformer, comprising:

[0070] Analyze the short-circuit operation of the main transformer and draw a hexagonal diagram to analyze the CT polarity and main transformer wiring group;

[0071] Add the short-circuit voltage of the transformer to the medium-voltage side, so that the high-voltage side and the low-voltage side are short-circuited, and detect the three-phase current of the secondary winding of the transformer;

[0072] Disconnect one of the phase voltages to allow the main transformer to generate zero-sequence current, and check the N line of the secondary winding of the transformer to obtain the main transformer connection group;

[0073] Open both sides of the short circuit of the transformer and detect the voltage transformation ratio of the transformer;

[0074] Compare and verify the three-phase current / main transformer connection group and voltage ratio with the transformer calibration value.

[0075] In the embodiment of the present invention, the short-circuit voltage percentage Vs% given on the transformer nameplate is the percentage of the voltage drop generated on the impedance when the transformer passes the rated current. For a large-capacity transformer, the resistance of its winding is much smaller than the reactance, and it can be approximately considered that the short-circuit reactance Vx%=Vs%, simulating a short-circuit current generated by a main transformer short circuit.

[0076] By comparison and calculation, it is a more reasonable choice to add voltage to the medium voltage side. If it is added to the high voltage side, the primary current obtained is too small to be measured. If it is added to the low voltage side, the current obtained on the low voltage side is too large. Sometimes there is no power supply with sufficient capacity on site, so the voltage is added to the medium voltage side to short-circuit the high and low voltage sides.

[0077] See also Figure 2 In step 101, the short-circuit operation of the main transformer is analyzed, and a hexagonal diagram is drawn to analyze the CT polarity and the main transformer connection group, specifically including:

[0078] When the main transformer is in short-circuit operation, it is equivalent to an inductor element. With the line voltage as a fixed reference, the primary polarity terminal P1 of the high-resistance line-side bushing CT is pointed to the sky, the secondary is positively drawn, and the secondary current flows out from the same-name terminal S1. At this time, the angle measured is that the voltage leads the secondary current of the line-side CT by 90°;

[0079] Add positive sequence to the three-phase AC mains on the medium voltage side and make a theoretical vector diagram of phase A;

[0080] Take U 中A Fixed as the reference voltage phasor, rotating counterclockwise to U 中A The angle between 中A The angle of the leading current; at this time, it can be known that the inductive transformer U 中A Ahead I 中 The angle is 90°, and the secondary current at the a-end of the high side, common side, and low voltage side is proportional to I 中 The angle difference is 180°; I 中 The vector magnitude is I 高 with I 公 Sum of amplitudes, opposite angles, I 高 with I 公 The angles of I are all 270°; 低开关 The angle is 240°; 低绕组a The angle is 270°; 低绕组x It is the non-polarity end of the primary winding on the low voltage side, and its angle is opposite to the polarity end CT, so I 低绕组x The angle is 90°;

[0081] By carrying out the primary current flow test of the main transformer as mentioned above and measuring the amplitude and phase of the secondary current of the bushings on each side of the main transformer, the polarity and transformation ratio of the bushing current transformer can be determined.

[0082] Add the short-circuit voltage of the transformer to the medium-voltage side, so that the high-voltage side and the low-voltage side are short-circuited, and detect the three-phase current of the secondary winding of the transformer; specifically include:

[0083] The short-circuit voltage percentage Vs% given on the transformer nameplate is the percentage of the voltage drop generated on the impedance when the transformer passes the rated current. For large-capacity transformers, the short-circuit reactance Vx% = Vs%, simulating a short-circuit current generated by a main transformer short circuit.

[0084] Calculation of short-circuit impedance voltage on each side:

[0085]

[0086] Among them: V1%, V2%, V3% are the percentages of short-circuit voltage on the high, middle and low sides of the main transformer respectively;

[0087] V 1-2 %、V 2-3%、V 1-3 % are the percentages of the short-circuit voltages of high to medium, medium to low, and high to low of the main transformer as provided on the manufacturer's nameplate;

[0088] See also Figure 3 , is the equivalent circuit diagram of the main transformer when the power supply is added to the medium voltage side. In the calculation of the power system, the equivalent circuit of the transformer often moves the excitation branch forward to the power supply side. If the medium voltage side is pressurized as shown in the above figure, the excitation branch is moved to the medium voltage side. Calculation of equivalent reactance on each side returned to the medium voltage side: (the following are all single-phase calculations)

[0089]

[0090] Among them: X1, X2, and X3 are the equivalent reactances of the high, middle, and low sides of the main transformer respectively;

[0091] VN: voltage value of the medium voltage side of the main transformer at this gear, in kV;

[0092] S N : Rated capacity of main transformer, unit KVA;

[0093] Add a three-phase symmetrical 220V AC voltage to the medium voltage side, and calculate the current on each side based on the equivalent circuit diagram of the main transformer:

[0094]

[0095] I3′=I2-I1′

[0096] I2 is the actual value on the medium voltage side, I1′ is the per-unit value on the high voltage side, and I3′ is the per-unit value on the low voltage side. The per-unit value needs to be converted to the corresponding voltage level side to obtain the current generated by the actual value on each side.

[0097] In the embodiment of the present invention, the short-circuit voltage of the transformer is added to the medium-voltage side, so that the high-voltage side and the low-voltage side are short-circuited, and the three-phase current of the secondary winding of the transformer is detected; specifically, the method includes:

[0098] A balanced 380V voltage is added to the medium voltage side of the main transformer, and currents of equal amplitude and positive angle sequence of a certain magnitude are obtained in the three phases of the secondary winding of each CT.

[0099] By adding a balanced 380V voltage to the medium voltage side of the main transformer, a current with equal amplitude and positive angle sequence can be obtained in the three phases of the secondary winding of each CT. However, since it is a balanced power supply, it is impossible to check whether the N line of the secondary current loop is correct. Therefore, after the three-phase inspection, one of the phase voltages should be disconnected to allow the main transformer to generate zero-sequence current, and then the N line of the secondary winding of each CT should be checked together.

[0100] Disconnect one phase voltage to make the main transformer generate zero-sequence current, and check the N line of the secondary winding of the transformer to obtain the main transformer connection group; specifically including:

[0101] By checking whether the differential current sampling value is zero, even if the collected current value is small, when the polarity is used incorrectly, the current superposition differential current value is obvious; it can be determined that the polarity of the primary equipment of the main transformer and the polarity of the secondary protection device are incorrectly matched; by measuring the phase difference between the low-voltage bushing CT current and the CT current at the low-voltage side switch, the main transformer connection group can be determined.

[0102] Since it is a balanced 380V voltage, the open triangle voltage is 0V, so it is impossible to check whether the cable core connection from the PT terminal box to the indoor voltage interface panel is correct. Therefore, after checking the zero-sequence current of the main transformer, keep disconnecting one of the phase voltages and continue to check the unbalance of the open triangle voltage.

[0103] That is, disconnect one of the phase voltages to allow the main transformer to generate zero-sequence current and check the N line of the secondary winding of the transformer; it also includes:

[0104] Keep one phase voltage disconnected to detect the unbalance of the open triangle voltage.

[0105] In order to better inspect the main transformer and its three-side voltage circuits, after checking the current circuit, the two sides of the transformer that were originally short-circuited can be opened. At this time, due to the voltage transformation ratio of the transformer, the PT secondary voltages on the high, medium and low sides can be measured to check the correctness of the open delta connection.

[0106] Embodiment 2

[0107] Figure 4 This is a schematic diagram of the 500kV Meilin transformer #1 autotransformer and its three-side connection. The voltage is applied to the rear end of the 2001 switch on the medium voltage side, and the busbar switch is opened; the 503117 and 503227 ground switches on the high voltage side are closed, the 5031 and 5032 switches are closed, and the 50312 and 50321 switches are closed; the 301 switch on the low voltage side is closed, the 3016 switch is closed, and the 3117 IM busbar ground switch on the low voltage side is closed. The neutral point of the autotransformer is grounded. The primary P1 terminal of each switch CT and the main transformer bushing CT is marked with "*" in the figure. The secondary winding tap current of all CTs is drawn from the same-name terminal S1 to the secondary load equipment (protection, measurement, metering, etc.).

[0108] Make a hexagonal diagram to analyze the CT polarity and main transformer wiring group: when the main transformer is short-circuited, it can be approximately regarded as an inductive element, just like the line is running with high-voltage reactor at no-load. If the line voltage is fixed as a reference, the primary polarity terminal P1 of the high-voltage reactor line-side bushing CT points to the sky, the secondary is positively drawn, and the secondary current flows out from the terminal S1 of the same name. At this time, the measured angle is that the voltage leads the secondary current of the line-side CT by 90°.

[0109] The specific operation method is as follows:

[0110] The short-circuit impedance provided on the nameplate of the main transformer manufacturer is used to accurately calculate the short-circuit current of the main transformer. The method of adding AC 380V voltage on the medium voltage side to make the main transformer generate short-circuit current is used to check the correctness of the main transformer differential circuit and wiring group.

[0111] The switches, knife switches and earth switches in the substation switch yard are used to perform switching operations to simulate a short circuit in the main transformer. The main purpose is to allow primary current to flow through the main transformer bushing CT and the switches CT on the three sides of the main transformer, thereby generating current in the secondary winding.

[0112] Using the A-phase voltage of the added AC 380V power supply as a reference, measure the magnitude and angle of the secondary current of each winding.

[0113] Draw a hexagonal diagram in advance for analysis and compare it with the test results to determine whether the CT ratio and polarity are correct and whether the main transformer wiring group is correct.

[0114] When the high and low sides of the main transformer are open, the transformation ratio of the PTs on the three sides of the main transformer and the correctness of the secondary voltage circuit can be checked at the same time by adding 380V voltage to the medium voltage side.

[0115] The parameters of the autotransformer installed in this 500kV Meilin substation are as follows:

[0116] Model:ODFS-334000 / 550

[0117] Manufacturer: Xi'an XD Transformer Co., Ltd.

[0118] Rated voltage:

[0119] high pressure: Medium pressure: Low voltage: 36.75kV

[0120] Single-phase rated capacity (when cooling method is ONAF):

[0121] High voltage: 334000kVA

[0122] Medium voltage: 334000kVA

[0123] Low voltage: 80000kVA

[0124] Wiring group: Yna0d11

[0125] Nameplate short-circuit impedance voltage: (three-phase average value)

[0126] V 1-2 % = 13.81%

[0127] V 1-3 % = 57.13%

[0128] V 2-3 % = 39.41%

[0129] Theoretical calculation of primary current of main transformer

[0130] Calculation of short-circuit impedance voltage on each side:

[0131]

[0132] Referred to the medium voltage side (V N =230kV) calculation of equivalent reactance on each side: (the following are all single-phase calculations)

[0133]

[0134] Add a three-phase symmetrical 220V AC voltage to the medium voltage side and calculate the current on each side: (ignore the transformer excitation current)

[0135]

[0136] I3'=I2-I1'=44.04-31.88=12.16A

[0137] Due to magnetic induction, the actual current on the high side and low side is calculated as:

[0138]

[0139] Since the low-pressure side is connected in a triangle, the internal

[0140]

[0141] According to Kirchhoff's current law KCL, the current flowing through the common winding is:

[0142] I 公 =I2-I1=44.04-13.97=30.07A

[0143] It only took 3.5 hours from the test wiring to the completion of data measurement and collection. The actual measured current on the medium voltage side is consistent with the theoretical calculation. (Theoretical calculation on the medium voltage side: 44.04A)

[0144] The measured data table is as follows:

[0145] Taking UA=220V as reference, the primary coil of the transformer is equivalent to an inductive load. Since the medium voltage side needs to provide excitation current, and the loss when flowing through the equipment, especially the circulating current heating loss of the triangle connection on the low voltage side, the primary current is slightly different from the actual current. Through angle analysis, it can be judged that the polarity of the main transformer CT is correct.

[0146] Table 9-1 CT measurement data table on each side of the main transformer

[0147]

[0148]

[0149] Since the deviation between the theoretical angle diagram on each side of the main transformer and the actual measured angle was between 5 and 10°, which was within a reasonable range, the primary voltage test on the main transformer body successfully checked the differential current circuit of the main transformer and ensured that the circuit was correct.

[0150] Through inspection, it was found that the nameplate of the autotransformer was wrong. The transformation ratio of the common bushing CT in the nameplate was 1500 / 5, but the actual current flow inspection found that the CT transformation ratio should be 1500 / 1, and it was verified by the manufacturer that it should be 1500 / 1.

[0151] Embodiment 3

[0152] See also Figure 5 The present invention also provides an autotransformer connection group verification device, comprising:

[0153] Theoretical analysis module 201 analyzes the short-circuit operation of the main transformer and draws a hexagonal diagram to analyze the CT polarity and the main transformer wiring group;

[0154] The current detection module 202 adds the short-circuit voltage of the transformer to the medium voltage side, so that the high voltage side and the low voltage side are short-circuited, and detects the three-phase current of the secondary winding of the transformer;

[0155] The connection group detection module 203 disconnects one of the phase voltages to allow the main transformer to generate zero-sequence current, and checks the N line of the secondary winding of the transformer to obtain the connection group of the main transformer;

[0156] The voltage transformation ratio detection module 204 opens the short-circuited two sides of the transformer to detect the voltage transformation ratio of the transformer;

[0157] The verification and analysis module 205 compares and verifies the three-phase current / main transformer connection group and voltage transformation ratio with the transformer calibration value.

[0158] The various variations and specific examples of the autotransformer wiring group verification method in the aforementioned embodiment are also applicable to an autotransformer wiring group verification device in this embodiment. Through the aforementioned detailed description of the autotransformer wiring group verification method, those skilled in the art can clearly understand the autotransformer wiring group verification device in this embodiment, so for the sake of brevity of the specification, it will not be described in detail here.

[0159] Embodiment 4

[0160] The present invention also provides an electronic device, which includes a processor at the hardware level, and optionally also includes an internal bus, a network interface, and a memory. The memory may include a memory, such as a high-speed random access memory (RAM), and may also include a non-volatile memory (non-volatile memory), such as at least one disk storage, etc. Of course, the electronic device may also include hardware required for other services.

[0161] The processor, network interface and memory can be interconnected through an internal bus, which can be an ISA (Industry Standard Architecture) bus, a PCI (Peripheral Component Interconnect) bus or an EISA (Extended Industry Standard Architecture) bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc.

[0162] The memory is used to store the program. Specifically, the program may include a program code, and the program code includes a computer operation instruction. The memory may include a memory and a non-volatile memory, and provides instructions and data to the processor.

[0163] The processor reads the corresponding computer program from the non-volatile memory into the memory and then runs it, forming a protective pressure plate monitoring device at the logical level. The processor executes the program stored in the memory and is specifically used to perform the following operations:

[0164] Add the short-circuit voltage of the transformer to the medium-voltage side, so that the high-voltage side and the low-voltage side are short-circuited, and detect the three-phase current of the secondary winding of the transformer;

[0165] Disconnect one of the phase voltages to allow the main transformer to generate zero-sequence current, and check the N line of the secondary winding of the transformer to obtain the main transformer connection group;

[0166] Open both sides of the short circuit of the transformer and detect the voltage transformation ratio of the transformer;

[0167] Compare and verify the three-phase current / main transformer connection group and voltage ratio with the transformer calibration value.

[0168] The method performed by the autotransformer wiring group verification device disclosed in the third embodiment can be applied to a processor or implemented by a processor. The processor may be an integrated circuit chip with signal processing capabilities. In the implementation process, each step of the above method can be completed by an integrated logic circuit of hardware in the processor or an instruction in the form of software. The above processor can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components. The methods, steps and logic block diagrams disclosed in one or more embodiments of the present application can be implemented or executed. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor, etc. The steps of the method disclosed in one or more embodiments of the present application can be directly embodied as a hardware decoding processor for execution, or a combination of hardware and software modules in the decoding processor for execution. The software module can be located in a storage medium mature in the art such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory, or an electrically erasable programmable memory, a register, etc. The storage medium is located in the memory, and the processor reads the information in the memory and completes the steps of the above method in combination with its hardware.

[0169] Of course, in addition to software implementation methods, the electronic device of the present application does not exclude other implementation methods, such as logic devices or a combination of software and hardware, etc. That is to say, the execution subject of the following processing flow is not limited to each logic unit, but can also be hardware or logic devices.

[0170] Embodiment 5

[0171] The embodiment of the present application also provides a computer-readable storage medium, which stores one or more programs, wherein the one or more programs include instructions, which, when executed by a portable electronic device including a plurality of application programs, enable the portable electronic device to execute Figure 1 The method of the embodiment shown is specifically used to perform the following operations:

[0172] Add the short-circuit voltage of the transformer to the medium-voltage side, so that the high-voltage side and the low-voltage side are short-circuited, and detect the three-phase current of the secondary winding of the transformer;

[0173] Disconnect one of the phase voltages to allow the main transformer to generate zero-sequence current, and check the N line of the secondary winding of the transformer to obtain the main transformer connection group;

[0174] Open both sides of the short circuit of the transformer and detect the voltage transformation ratio of the transformer;

[0175] Compare and verify the three-phase current / main transformer connection group and voltage ratio with the transformer calibration value.

[0176] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. The method for checking the connection group of the autotransformer is characterized by: include: Analyze the short-circuit operation of the main transformer and draw a hexagonal diagram to analyze the CT polarity and main transformer wiring group; Add the short-circuit voltage of the transformer to the medium-voltage side, so that the high-voltage side and the low-voltage side are short-circuited, and detect the three-phase current of the secondary winding of the transformer; Disconnect one of the phase voltages to allow the main transformer to generate zero-sequence current, and check the N line of the secondary winding of the transformer to obtain the main transformer connection group; Open both sides of the short circuit of the transformer and detect the voltage transformation ratio of the transformer; Compare and verify the three-phase current / main transformer connection group and voltage ratio with the transformer calibration value.

2. The method for checking the connection group of an autotransformer according to claim 1, characterized in that: The analysis of the short-circuit operation of the main transformer and the drawing of a hexagonal diagram to analyze the CT polarity and the main transformer wiring group specifically include: When the main transformer is in short-circuit operation, it is equivalent to an inductor element. With the line voltage as a fixed reference, the primary polarity terminal P1 of the high-resistance line-side bushing CT is pointed to the sky, the secondary is positively drawn, and the secondary current flows out from the same-name terminal S1. At this time, the angle measured is that the voltage leads the secondary current of the line-side CT by 90°; Add positive sequence to the three-phase AC mains on the medium voltage side and make a theoretical vector diagram of phase A; Take U 中A Fixed as the reference voltage phasor, rotating counterclockwise to U 中A The angle between 中A The angle of the leading current; at this time, it can be known that the inductive transformer U 中A Ahead I 中 The angle is 90°, and the secondary current at the a-end of the high side, common side, and low voltage side is proportional to I 中 The angle difference is 180°; I 中 The vector magnitude is I 高 with I 公 Sum of amplitudes, opposite angles, I 高 with I 公 The angles of I are all 270°; 低开关 The angle is 240°; 低绕组a The angle is 270°; 低绕组x It is the non-polarity end of the primary winding on the low voltage side, and its angle is opposite to the polarity end CT, so I 低绕组x The angle is 90°; By carrying out the primary current flow test of the main transformer and measuring the amplitude and phase of the secondary current of the bushings on each side of the main transformer, the polarity and transformation ratio of the bushing current transformer can be determined.

3. The method for checking the connection group of an autotransformer according to claim 1, characterized in that: The short-circuit voltage of the transformer is added to the medium-voltage side to short-circuit the high-voltage side and the low-voltage side, and the three-phase current of the secondary winding of the transformer is detected; specifically Include: Specifically include: The short-circuit voltage percentage Vs% given on the transformer nameplate is the percentage of the voltage drop generated on the impedance when the transformer passes the rated current. For large-capacity transformers, the short-circuit reactance Vx% = Vs%, simulating a short-circuit current generated by a main transformer short circuit. Calculation of short-circuit impedance voltage on each side: Among them: V1%, V2%, V3% are the percentages of short-circuit voltage on the high, middle and low sides of the main transformer respectively; V 1-2 %、V 2-3 %、V 1-3 % are the percentages of the short-circuit voltages of high to medium, medium to low, and high to low of the main transformer as provided on the manufacturer's nameplate; Calculation of equivalent reactance on each side converted to the medium voltage side: (the following are all single-phase calculations) Among them: X1, X2, and X3 are the equivalent reactances of the high, middle, and low sides of the main transformer respectively; VN: voltage value of the medium voltage side of the main transformer at this gear, in kV; S N : Rated capacity of main transformer, unit: KVA; Add a three-phase symmetrical 220V AC voltage to the medium voltage side and calculate the current on each side: I3′=I2-I1′ I2 is the actual value on the medium voltage side, I1′ is the per-unit value on the high voltage side, and I3′ is the per-unit value on the low voltage side. The per-unit value needs to be converted to the corresponding voltage level side to obtain the current generated by the actual value on each side.

4. The method for checking the connection group of an autotransformer according to claim 1, characterized in that: The analysis of the short-circuit operation of the main transformer and the drawing of a hexagonal diagram to analyze the CT polarity and the main transformer wiring group specifically include: A balanced 380V voltage is added to the medium voltage side of the main transformer, and three-phase currents with equal amplitude and positive angle sequence are obtained through three-phase detection of the secondary windings of each CT.

5. The method for checking the connection group of an autotransformer according to claim 1, characterized in that: The method of disconnecting one phase voltage to allow the main transformer to generate zero-sequence current and inspecting the N line of the secondary winding of the transformer to obtain the main transformer connection group includes: By checking whether the differential current sampling value is zero, even if the collected current value is small, when the polarity is used incorrectly, the current superposition differential current value is obvious; it can be determined that the polarity of the primary equipment of the main transformer and the polarity of the secondary protection device are incorrectly matched; by measuring the phase difference between the low-voltage bushing vT current and the CT current at the low-voltage side switch, the main transformer connection group can be determined.

6. The method for checking the connection group of an autotransformer according to claim 4, characterized in that: The method of disconnecting one phase voltage to allow the main transformer to generate zero-sequence current and inspecting the N line of the secondary winding of the transformer also includes: Keep one phase voltage disconnected to detect the unbalance of the open triangle voltage.

7. The method for checking the connection group of an autotransformer according to claim 1, characterized in that: The step of opening both sides of the short circuit of the transformer and detecting the voltage transformation ratio of the transformer specifically includes: Open the short-circuited sides of the transformer, detect the voltage transformation ratio of the transformer, measure the PT secondary voltage on the high voltage side / medium voltage side / low voltage side, and verify the correctness of the open delta connection.

8. The autotransformer connection group verification device is characterized by: The method for verifying the connection group of an autotransformer as claimed in any one of claims 1 to 7 comprises: Theoretical analysis module analyzes the short-circuit operation of the main transformer and draws a hexagonal diagram to analyze the CT polarity and main transformer wiring group; The current detection module adds the short-circuit voltage of the transformer to the medium-voltage side, causing the high-voltage side and the low-voltage side to be short-circuited, and detects the three-phase current of the secondary winding of the transformer; The connection group detection module disconnects one of the phase voltages to allow the main transformer to generate zero-sequence current, and checks the N line of the secondary winding of the transformer to obtain the connection group of the main transformer; The voltage transformation ratio detection module opens the short-circuited sides of the transformer to detect the voltage transformation ratio of the transformer; The verification and analysis module compares and verifies the three-phase current / main transformer connection group and voltage ratio with the transformer calibration value.

9. An electronic device, characterized in that: The invention comprises a processor, a memory and a computer program stored in the memory and executable on the processor, wherein when the computer program is executed by the processor, the method for verifying the connection group of an autotransformer as claimed in any one of claims 1 to 7 is implemented.

10. A computer-readable storage medium, characterized in that: The storage medium stores a computer program, and when the computer program is executed by the processor, the following process is implemented: Analyze the short-circuit operation of the main transformer and draw a hexagonal diagram to analyze the CT polarity and main transformer wiring group; Add the short-circuit voltage of the transformer to the medium-voltage side, so that the high-voltage side and the low-voltage side are short-circuited, and detect the three-phase current of the secondary winding of the transformer; Disconnect one of the phase voltages to allow the main transformer to generate zero-sequence current, and check the N line of the secondary winding of the transformer to obtain the main transformer connection group; Open both sides of the short circuit of the transformer and detect the voltage transformation ratio of the transformer; Compare and verify the three-phase current / main transformer connection group and voltage ratio with the transformer calibration value.

Images