Transformer multi-side gear real-time measuring and calculating method and system based on sampling current

Abstract

The invention discloses a transformer multi-side gear real-time measuring and calculating method and system based on sampling current, and the method comprises the steps: collecting the secondary current of a current transformer at each side of a transformer, and calculating the converted primary current at each side of the transformer; according to the converted primary current of each side and transformer equipment parameters, calculating a comprehensive gear coefficient of a gear shifting side of the transformer; the actual gear of the gear shifting side of the transformer is calculated through the comprehensive gear coefficient; the system comprises an acquisition module, a comprehensive gear calculation module and an actual gear calculation module. According to the magnetomotive force balance principle, a relation equation set of currents and gear coefficients of all sides of a transformer is established, and a three-phase gear coefficient and a comprehensive gear coefficient of the gear shifting side of the transformer are calculated; and establishing a current gear estimation criterion of the gear shifting side, and judging to obtain a current actual gear of the gear shifting side of the transformer according to the comprehensive gear coefficient, so that the gear real-time calculation of the multi-side gear shifting transformer can be realized by only depending on the magnitude of current of each side of the transformer without depending on the voltage.

Description

Technical Field

[0001] This invention relates to the field of power system relay protection, and in particular to a method and system for real-time calculation of multiple tap positions of a transformer based on sampled current. Background Technology

[0002] Adjusting the tap position of a transformer in a power system directly affects the transformer's output voltage and is one of the important means of maintaining system voltage stability. Transformer tap adjustment involves changing the position of the tap changer to alter the turns ratio of the transformer windings, thereby maintaining the output voltage within a specified range when the grid voltage fluctuates or the load changes.

[0003] The tap position information of a transformer tap changer is a crucial parameter in the transformer tap adjustment process. Accurate tap position information is fundamental to tap position adjustment and is typically transmitted to the control equipment in BCD code. In substation automation control systems, the tap position can be automatically adjusted based on changes in grid voltage and the current tap position information, reducing human error and further improving the stability and reliability of the power system. Abnormal tap position information transmission may cause the control system to malfunction, leading to voltage fluctuations and even affecting the stable and safe operation of the system.

[0004] Therefore, a real-time calculation method for multiple tap positions of a transformer that does not rely on information sent from the tap changer is needed. This method can verify the sent tap position information in real time and prevent unexpected tap position adjustments due to abnormal tap position information. To this end, a real-time calculation method for multiple tap positions of a transformer based on sampled current is proposed. Summary of the Invention

[0005] Purpose of the invention: The purpose of this invention is to provide a method and system for real-time calculation of multiple tap positions of a transformer based on sampled current.

[0006] Technical solution: The real-time calculation method for multiple tap positions of a transformer based on sampled current, as described in this invention, includes the following steps:

[0007] Step 1: Collect the secondary current of the current transformers on each side of the transformer, and calculate the converted primary current of the transformer on each side;

[0008] Step 2: Calculate the comprehensive tap position coefficient of the transformer tapping side based on the converted primary current and transformer equipment parameters on each side;

[0009] Step 3: Calculate the actual tap position on the transformer tapping side by using the comprehensive tap position coefficient.

[0010] Further, step 1 includes:

[0011] The currents on the high-voltage, medium-voltage, and low-voltage sides of the transformer are collected. The currents on the delta-connected and star-connected sides are uniformly converted, and then converted using the current transformer ratio to obtain the primary current on the high-voltage side. The medium voltage side current is The low-voltage side current is Let n be the three phases of the current, n = 1, 2, 3...N, where N is the number of sampling points within an analysis window.

[0012] Further, step 2 includes:

[0013] Step 2.1: Transformers typically only have the high-voltage and medium-voltage sides as tap-changing sides. Based on the magnetomotive force balance principle, the current relationship between the transformer sides can be obtained as follows:

[0014]

[0015] Among them, U h U m and U l These are the rated voltages of the high-voltage side, medium-voltage side, and low-voltage side of the transformer, respectively. and These are the phase shift coefficients for the high-pressure side and the medium-pressure side, respectively.

[0016] Step 2.2: Extract the tap position coefficient on the tap adjustment side to obtain the relationship between the voltage and current on each side of the transformer and the tap position coefficient on the tap adjustment side:

[0017]

[0018] in,

[0019] Step 2.3: Calculate the gear ratio coefficient for the gear shift side:

[0020]

[0021] in, It is a generalized inverse matrix, i.e.

[0022] Step 2.4: Calculate the overall gear ratio coefficient on the gear shift side. for:

[0023]

[0024] in, and These are the combined gear ratios for the high-pressure side and the medium-pressure side, respectively.

[0025] Further, step 3 includes:

[0026] Step 3.1: Based on the transformer nameplate information, obtain the different tap positions p on the tap adjustment side. xThe corresponding rated voltage U xp , and p xmin ≤p x ≤P xmax p xmin p xmax For the minimum and maximum tap positions on the transformer tapping side, the actual tap position coefficients for different tap positions on the tapping side are calculated as follows:

[0027] k x [p x ] = U x [p x ] / U x

[0028] Where, k x [p x [For gear adjustment side p] x The actual gear ratio when the gear is selected; x takes h and m, representing the high-voltage side and medium-voltage side of the transformer, respectively;

[0029] Step 3.2: Based on the comprehensive gear ratio coefficient of the gear shifting side and the actual gear ratio coefficient of the gear shifting side, establish the current gear estimation criterion for the gear shifting side as follows:

[0030] Criterion 1: When p xmin <p x <p xmax When, satisfy

[0031] Criterion 2: When p x =p xmax When, satisfy

[0032] Criterion 3: When p x =p xmin When, satisfy

[0033] When any one of the criteria 1 to 3 is met, the current gear position on the gear adjustment side is output as px;

[0034] If none of the conditions 1 to 3 are met, the current gear position estimation on the gear shifting side is incorrect, and a gear position abnormality alarm is issued.

[0035] The real-time transformer multi-strip position measurement system based on sampled current described in this invention includes:

[0036] The data acquisition module is used to acquire the secondary current of the current transformers on each side of the transformer and calculate the converted primary current of each side of the transformer.

[0037] The integrated tap position calculation module is used to calculate the integrated tap position coefficient of the transformer tap position based on the converted primary current and transformer equipment parameters on each side.

[0038] The actual tap position calculation module is used to calculate the actual tap position on the transformer tap adjustment side by using the comprehensive tap position coefficient.

[0039] Furthermore, the acquisition module includes:

[0040] The currents on the high-voltage, medium-voltage, and low-voltage sides of the transformer are collected. The currents on the delta-connected and star-connected sides are uniformly converted, and then converted using the current transformer ratio to obtain the primary current on the high-voltage side. The medium voltage side current is The low-voltage side current is Let n be the three phases of the current, n = 1, 2, 3...N, where N is the number of sampling points within an analysis window.

[0041] Furthermore, the comprehensive tap position calculation module calculates the comprehensive tap position coefficient of the transformer tap-adjustment side based on the converted primary current and transformer equipment parameters on each side, including:

[0042] Step 2.1: Transformers typically only have the high-voltage and medium-voltage sides as tap-changing sides. Based on the magnetomotive force balance principle, the current relationship between the transformer sides can be obtained as follows:

[0043]

[0044] Among them, U h U m and U l These are the rated voltages of the high-voltage side, medium-voltage side, and low-voltage side of the transformer, respectively. and These are the phase shift coefficients for the high-pressure side and the medium-pressure side, respectively.

[0045] Step 2.2: Extract the tap position coefficient on the tap adjustment side to obtain the relationship between the voltage and current on each side of the transformer and the tap position coefficient on the tap adjustment side:

[0046]

[0047] in,

[0048] Step 2.3: Calculate the gear ratio coefficient for the gear shift side:

[0049]

[0050] in, It is a generalized inverse matrix, i.e.

[0051] Step 2.4: Calculate the overall gear ratio coefficient on the gear shift side. for:

[0052]

[0053] in, and These are the combined gear ratios for the high-pressure side and the medium-pressure side, respectively.

[0054] Furthermore, the actual tap position calculation module is used to calculate the actual tap position on the transformer tap adjustment side by means of a comprehensive tap position coefficient, including:

[0055] Step 3.1: Based on the transformer nameplate information, obtain the different tap positions p on the tap adjustment side. x The corresponding rated voltage U xp , and p xmin ≤p x ≤p xmax p xmin p xmax For the minimum and maximum tap positions on the transformer tapping side, the actual tap position coefficients for different tap positions on the tapping side are calculated as follows:

[0056] k x [p x ] = U x [p x ] / U x

[0057] Where, k x [p x [For gear adjustment side p] x The actual gear ratio when the gear is selected; x takes h and m, representing the high-voltage side and medium-voltage side of the transformer, respectively;

[0058] Step 3.2: Based on the comprehensive gear ratio coefficient of the gear shifting side and the actual gear ratio coefficient of the gear shifting side, establish the current gear estimation criterion for the gear shifting side as follows:

[0059] Criterion 1: When p xmin <p x <p xmax When, satisfy

[0060] Criterion 2: When p x =p xmax When, satisfy

[0061] Criterion 3: When p x =p xmin When, satisfy

[0062] When any one of the criteria 1 to 3 is met, the current gear position on the gear adjustment side is output as px;

[0063] If none of the conditions 1 to 3 are met, the current gear position estimation on the gear shifting side is incorrect, and a gear position abnormality alarm is issued.

[0064] Furthermore, when the processor executes the program, it implements a method for real-time calculation of the multi-slot position of a transformer based on the sampled current.

[0065] Furthermore, the computer program is designed to implement a real-time calculation method for multiple tap positions of a transformer based on sampled current during runtime.

[0066] Beneficial Effects: Compared with the prior art, the present invention has the following significant advantages: The present invention collects the secondary current of the current transformers on each side of the transformer, and obtains the converted primary current of each side of the transformer through unified conversion of delta and star connections and conversion of the current transformer ratio; establishes a set of equations relating the current on each side of the transformer to the tap position coefficient based on the principle of magnetomotive force balance, then calculates the three-phase tap position coefficient of the tap position on the tap position side of the transformer, and further calculates the comprehensive tap position coefficient of the tap position side; establishes the current tap position estimation criterion of the tap position side, and determines the current actual tap position of the tap position side of the transformer based on the comprehensive tap position coefficient; the present invention does not rely on voltage, but only on the current on each side of the transformer to realize the real-time calculation of the tap position of multi-sided tap-adjusting transformers. Attached Figure Description

[0067] Figure 1 This is a diagram showing the structure of the transformer with multi-side tap adjustment and the arrangement of the current transformer according to the present invention.

[0068] Figure 2 The above are the primary current waveforms of the transformers on each side of the transformer according to an embodiment of the present invention.

[0069] Figure 3 This is a diagram showing the real-time calculation results of the tap positions on the high-voltage and medium-voltage sides of the transformer in an embodiment of the present invention. Detailed Implementation

[0070] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0071] The real-time calculation method for multiple tap positions of a transformer based on sampled current, as described in this invention, includes the following steps:

[0072] Step 1: Collect the secondary current of the current transformers on each side of the transformer, and calculate the converted primary current of the transformer on each side;

[0073] The currents on the high-voltage, medium-voltage, and low-voltage sides of the transformer are collected. The currents on the delta-connected and star-connected sides are uniformly converted, and then converted using the current transformer ratio to obtain the primary current on the high-voltage side. The medium voltage side current is The low-voltage side current is Let n be the three phases of the current, n = 1, 2, 3...N, where N is the number of sampling points within an analysis window.

[0074] Step 2: Calculate the comprehensive tap position coefficient of the transformer tapping side based on the converted primary current and transformer equipment parameters on each side;

[0075] Step 2.1: Transformers typically only have the high-voltage and medium-voltage sides as tap-changing sides. Based on the magnetomotive force balance principle, the current relationship between the transformer sides can be obtained as follows:

[0076]

[0077] Among them, U h U m and U l These are the rated voltages of the high-voltage side, medium-voltage side, and low-voltage side of the transformer, respectively. and These are the phase shift coefficients for the high-pressure side and the medium-pressure side, respectively.

[0078] Step 2.2: Extract the tap position coefficient on the tap adjustment side to obtain the relationship between the voltage and current on each side of the transformer and the tap position coefficient on the tap adjustment side:

[0079]

[0080] in,

[0081] Step 2.3: Calculate the gear ratio coefficient for the gear shift side:

[0082]

[0083] in, It is a generalized inverse matrix, i.e.

[0084] Step 2.4: Calculate the overall gear ratio coefficient on the gear shift side. for:

[0085]

[0086] in, and These are the combined gear ratios for the high-pressure side and the medium-pressure side, respectively.

[0087] Step 3: Calculate the actual tap position on the transformer tapping side by using the comprehensive tap position coefficient.

[0088] Step 3.1: Based on the transformer nameplate information, obtain the different tap positions p on the tap adjustment side. x The corresponding rated voltage U xp , and p xmin ≤p x ≤p xmax p xmin p xmax For the minimum and maximum tap positions on the transformer tapping side, the actual tap position coefficients for different tap positions on the tapping side are calculated as follows:

[0089] k x [p x ] = U x [p x ] / U x

[0090] Where, k x [p x [For gear adjustment side p] x The actual gear ratio when the gear is selected; x takes h and m, representing the high-voltage side and medium-voltage side of the transformer, respectively;

[0091] Step 3.2: Based on the comprehensive gear ratio coefficient of the gear shifting side and the actual gear ratio coefficient of the gear shifting side, establish the current gear estimation criterion for the gear shifting side as follows:

[0092] Criterion 1: When p xmin <p x <p xmax When, satisfy

[0093] Criterion 2: When p x =p xmax When, satisfy

[0094] Criterion 3: When p x =p xmin When, satisfy

[0095] When any one of criteria 1 to 3 is satisfied, the current gear position on the gear shifting side is p. x ;

[0096] If none of the conditions 1 to 3 are met, the current gear position estimation on the gear shifting side is incorrect, and a gear position abnormality alarm is issued.

[0097] To verify the accuracy and adaptability of the real-time transformer tap position calculation method based on sampled current, a transformer simulation model with multi-taper adjustment was built according to the above principles. The tap adjustment sides are the high-voltage side and the medium-voltage side. The three-phase structure of the transformer and the arrangement of the current transformers in the model are as follows: Figure 1 As shown in the figure. This embodiment uses a three-winding transformer with a connection group of YNynd11. The rated voltage on the high-voltage side is 220kV, the rated voltage on the medium-voltage side is 110kV, and the rated voltage on the low-voltage side is 35kV. The current transformer ratio on each side is 1000:1. Both the high-voltage and medium-voltage sides of the transformer can be adjusted via tap changers, with an adjustment range of ±8 taps × 1.25%. In the simulation, the tap changer on the high-voltage side is set to +4, and the tap changer on the medium-voltage side is set to -4. The primary current waveforms after conversion of the secondary currents of the current transformers on each side are shown in the figure. Figure 2As shown. The results of real-time calculation of the transformer high-voltage and medium-voltage tap positions using the technical solution of this invention are as follows. Figure 3 As shown, the high-pressure side gear is always stable at +4, the medium-pressure side gear is always stable at -4, and the real-time calculation result of the gear on the shift side is consistent with the actual value.

[0098] In summary, using the method described in this invention, the secondary currents of the current transformers on each side of the transformer are collected, and the equivalent primary currents on each side of the transformer are obtained through unified conversion between delta and star connections and transformation of the current transformer ratios. Secondly, based on the magnetomotive force balance principle, a set of equations relating the currents on each side of the transformer to the tap position coefficients is established. Subsequently, the three-phase tap position coefficients on the tap adjustment side of the transformer are calculated, and the comprehensive tap position coefficient on the tap adjustment side is further calculated. Finally, a criterion for estimating the current tap position on the tap adjustment side is established, and based on the comprehensive tap position coefficient, the current actual tap position on the tap adjustment side of the transformer is determined.

[0099] The real-time transformer multi-strip position measurement system based on sampled current described in this invention includes:

[0100] The data acquisition module is used to acquire the secondary current of the current transformers on each side of the transformer and calculate the converted primary current of each side of the transformer.

[0101] The integrated tap position calculation module is used to calculate the integrated tap position coefficient of the transformer tap position based on the converted primary current and transformer equipment parameters on each side.

[0102] The actual tap position calculation module is used to calculate the actual tap position on the transformer tap adjustment side by using the comprehensive tap position coefficient.

Claims

1. A method for real-time calculation of multiple tap positions of a transformer based on sampled current, characterized in that, Includes the following steps: Step 1: Collect the secondary current of the current transformers on each side of the transformer, and calculate the converted primary current of the transformer on each side; Step 2: Calculate the comprehensive tap position coefficient of the transformer tapping side based on the converted primary current and transformer equipment parameters on each side; Step 3: Calculate the actual tap position on the transformer tapping side by using the comprehensive tap position coefficient.

2. The method for real-time calculation of transformer multi-strip positions based on sampled current according to claim 1, characterized in that, Step 1 includes: The currents on the high-voltage, medium-voltage, and low-voltage sides of the transformer are collected. The currents on the delta-connected and star-connected sides are uniformly converted, and then converted using the current transformer ratio to obtain the primary current on the high-voltage side. The medium voltage side current is The low-voltage side current is Let n be the three phases of the current, n = 1, 2, 3...N, where N is the number of sampling points within an analysis window.

3. The method for real-time calculation of transformer multi-strip positions based on sampled current according to claim 1, characterized in that, Step 2 includes: Step 2.1: Transformers typically only have the high-voltage and medium-voltage sides as tap-changing sides. Based on the magnetomotive force balance principle, the current relationship between the transformer sides can be obtained as follows: Among them, U h U m and U l These are the rated voltages of the high-voltage side, medium-voltage side, and low-voltage side of the transformer, respectively. and These are the phase shift coefficients for the high-pressure side and the medium-pressure side, respectively. Step 2.2: Extract the tap position coefficient on the tap adjustment side to obtain the relationship between the voltage and current on each side of the transformer and the tap position coefficient on the tap adjustment side: in, Step 2.3: Calculate the gear ratio coefficient for the gear shift side: in, It is a generalized inverse matrix, i.e. Step 2.4: Calculate the overall gear ratio coefficient on the gear shift side. for: in, and These are the combined gear ratios for the high-pressure side and the medium-pressure side, respectively.

4. The method for real-time calculation of transformer multi-strip positions based on sampled current according to claim 1, characterized in that, Step 3 includes: Step 3.1: Based on the transformer nameplate information, obtain the different tap positions p on the tap adjustment side. x The corresponding rated voltage U xp , and p xmin ≤p x ≤P xmax p xmin p xmax For the minimum and maximum tap positions on the transformer tapping side, the actual tap position coefficients for different tap positions on the tapping side are calculated as follows: k x [p x ]=U x [p x ] / IN x Where, k x [p x [For gear adjustment side p] x The actual gear ratio when the gear is selected; x takes h and m, representing the high-voltage side and medium-voltage side of the transformer, respectively; Step 3.2: Based on the comprehensive gear ratio coefficient of the gear shifting side and the actual gear ratio coefficient of the gear shifting side, establish the current gear estimation criterion for the gear shifting side as follows: Criterion 1: When p xmin <p x <p xmax When, satisfy Criterion 2: When p x =P xmax When, satisfy Criterion 3: When p x =p xmin When, satisfy When any one of criteria 1 to 3 is satisfied, the current gear position on the gear shifting side is p. x ; If none of the conditions 1 to 3 are met, the current gear position estimation on the gear shifting side is incorrect, and a gear position abnormality alarm is issued.

5. A real-time measurement system for multiple tap positions of a transformer based on sampled current, characterized in that, include: The data acquisition module is used to acquire the secondary current of the current transformers on each side of the transformer and calculate the converted primary current of each side of the transformer. The integrated tap position calculation module is used to calculate the integrated tap position coefficient of the transformer tap position based on the converted primary current and transformer equipment parameters on each side. The actual tap position calculation module is used to calculate the actual tap position on the transformer tap adjustment side by using the comprehensive tap position coefficient.

6. The real-time transformer multi-strip position calculation system based on sampled current according to claim 5, characterized in that, The acquisition module includes: The currents on the high-voltage, medium-voltage, and low-voltage sides of the transformer are collected. The currents on the delta-connected and star-connected sides are uniformly converted, and then converted using the current transformer ratio to obtain the primary current on the high-voltage side. The medium voltage side current is The low-voltage side current is Let n be the three phases of the current, n = 1, 2, 3...N, where N is the number of sampling points within an analysis window.

7. The real-time transformer multi-strip position calculation system based on sampled current according to claim 5, characterized in that, The comprehensive tap position calculation module calculates the comprehensive tap position coefficient of the transformer tap-adjusting side based on the converted primary current and transformer equipment parameters on each side, including: Step 2.1: Transformers typically only have the high-voltage and medium-voltage sides as tap-changing sides. Based on the magnetomotive force balance principle, the current relationship between the transformer sides can be obtained as follows: Among them, U h U m and U l These are the rated voltages of the high-voltage side, medium-voltage side, and low-voltage side of the transformer, respectively. and These are the phase shift coefficients for the high-pressure side and the medium-pressure side, respectively. Step 2.2: Extract the tap position coefficient on the tap adjustment side to obtain the relationship between the voltage and current on each side of the transformer and the tap position coefficient on the tap adjustment side: in, Step 2.3: Calculate the gear ratio coefficient for the gear shift side: in, It is a generalized inverse matrix, i.e. Step 2.4: Calculate the overall gear ratio coefficient on the gear shift side. for: in, and These are the combined gear ratios for the high-pressure side and the medium-pressure side, respectively.

8. The real-time transformer multi-strip position measurement system based on sampled current according to claim 5, characterized in that, The actual tap position calculation module is used to calculate the actual tap position on the transformer tap adjustment side by means of a comprehensive tap position coefficient, including: Step 3.1: Based on the transformer nameplate information, obtain the different tap positions p on the tap adjustment side. x The corresponding rated voltage U xp , and p xmin ≤p x ≤p xmax p xmin p xmax For the minimum and maximum tap positions on the transformer tapping side, the actual tap position coefficients for different tap positions on the tapping side are calculated as follows: k x [p x ]=U x [p x ] / IN x Where, k x [p x [For gear adjustment side p] x The actual gear ratio when the gear is selected; x takes h and m, representing the high-voltage side and medium-voltage side of the transformer, respectively; Step 3.2: Based on the comprehensive gear ratio coefficient of the gear shifting side and the actual gear ratio coefficient of the gear shifting side, establish the current gear estimation criterion for the gear shifting side as follows: Criterion 1: When p xmin <p x <p xmax When, satisfy Criterion 2: When p x =p xmax When, satisfy Criterion 3: When p x =p xmin When, satisfy When any one of the criteria 1 to 3 is met, the current gear position on the gear adjustment side is output as px; If none of the conditions 1 to 3 are met, the current gear position estimation on the gear shifting side is incorrect, and a gear position abnormality alarm is issued.

9. An electronic device comprising a memory, a processor, and a program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the real-time calculation method for multiple tap positions of a transformer based on sampled current, as described in any one of claims 1-4.

10. A storage medium storing a computer program, characterized in that, The computer program is designed to implement, at runtime, the real-time calculation method for multiple tap positions of a transformer based on sampled current, as described in any one of claims 1 to 6.

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