Low voltage compensation method and device for autotransformer, medium and equipment

Abstract

The invention discloses an autotransformer low voltage compensation method, device, medium and equipment, and the method comprises the steps: integrating a compensation transformer and an autotransformer in an oil tank housing, and connecting a primary side coil of the compensation transformer and a voltage regulating coil of the autotransformer to form a magnet exciting coil; under the condition that a secondary side coil of the compensation transformer is connected with a low-voltage coil of the autotransformer in series, the excitation voltage of an excitation coil of the autotransformer at different tapping positions is calculated; based on the excitation voltage of the excitation coil of the autotransformer at different tapping positions, calculating the secondary side voltage of the secondary side coil of the compensation transformer of the autotransformer at different tapping positions; and calculating the low voltage of the autotransformer at different tapping positions, and superposing the low voltage with the secondary side voltage of the secondary side coil of the compensation transformer at different tapping positions of the autotransformer so as to compensate the low voltage of the autotransformer. According to the invention, the anti-short-circuit capability of the autotransformer can be improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of transformers, and in particular relates to a method, device, medium and equipment for compensating low voltage of an autotransformer. Background Art

[0002] The voltage regulating position of the traditional constant flux voltage regulating autotransformer is at the end of the series winding. The voltage level of the on-load tap changer of this structure is high. The on-load tap changer cannot be made into a three-phase integrated one. Three single-phase switches are required to be used in combination. The overall cost is relatively high, the transformer is large, and the internal leads of the transformer are complicated. Existing voltage regulation methods, such as the variable flux voltage regulation method using neutral point voltage regulation, usually encounter problems such as excessive high and low voltage ratio and small high and low voltage short-circuit impedance during voltage regulation. These problems will cause the transformer to be unable to meet the load demand during operation, thereby affecting the stability and safety of the power grid. Summary of the invention

[0003] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a method, device, medium and equipment for compensating low-voltage of an autotransformer, which can effectively compensate for the low-voltage of the autotransformer to improve the short-circuit resistance of the autotransformer.

[0004] To achieve the above objectives, the present disclosure provides the following technical solutions:

[0005] A method for compensating low-voltage autotransformer, comprising: under the condition that a compensating transformer and an autotransformer are integrated in an oil tank housing, a primary coil of the compensating transformer is connected to a voltage regulating coil of the autotransformer to form an excitation coil, and a secondary coil of the compensating transformer is connected in series with a low-voltage coil of the autotransformer,

[0006] Calculating the excitation voltage of the excitation coil of the autotransformer at different tap positions;

[0007] Calculating the secondary side voltage of the secondary side coil of the compensation transformer at different tap positions of the autotransformer based on the excitation voltage of the excitation coil at different tap positions of the autotransformer;

[0008] The low voltage of the autotransformer at different tap positions is calculated and superimposed with the secondary side voltage of the secondary side coil of the compensation transformer at different tap positions of the autotransformer to compensate for the low voltage of the autotransformer.

[0009] Optionally, calculating the excitation voltage of the excitation coil of the autotransformer at different tap positions includes the following steps: calculating the high voltage voltage of the autotransformer at different tap positions; calculating the excitation voltage of the excitation coil of the autotransformer at different tap positions based on the high voltage voltage of the autotransformer at different tap positions and the number of turns of the voltage regulating winding of the autotransformer.

[0010] Optionally, calculating the secondary side voltage of the secondary side coil of the compensation transformer based on the excitation voltage of the excitation coil of the autotransformer at different tap positions includes the following steps: calculating the transformation ratio of the compensation transformer; calculating the secondary side voltage of the secondary side coil of the compensation transformer at different tap positions of the autotransformer based on the transformation ratio of the compensation transformer and the excitation voltage of the excitation coil of the autotransformer at different tap positions.

[0011] The present disclosure also provides a low-voltage compensation device for an autotransformer, and the device applies the method described in any of the preceding items.

[0012] The present disclosure also provides an autotransformer low-voltage compensation system, the system comprising the device as described above.

[0013] The present disclosure also provides a storage medium comprising instructions, which, when executed on a computer, enables the computer to execute the method as described in any one of the preceding items.

[0014] The present disclosure also provides an electronic device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the method described in any of the preceding items when executing the program.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] The present invention adopts a built-in compensating transformer, which can solve the problem of excessive difference in the high-to-low voltage ratio of the variable flux voltage regulating autotransformer; and can effectively compensate for the low voltage of the autotransformer, thereby improving the short-circuit resistance of the autotransformer. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a flowchart of a low-voltage voltage compensation method for an autotransformer provided by an embodiment of the present disclosure;

[0018] Figure 2 is a schematic diagram of the positions of an autotransformer and a compensating transformer provided by an embodiment of the present disclosure;

[0019] Figure 3 It is a connection diagram of an autotransformer and a compensating transformer provided in another embodiment of the present disclosure. DETAILED DESCRIPTION

[0020] The following will refer to the attached Figures 1 to 3 Specific embodiments of the present disclosure are described in detail. Although specific embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0021] It should be noted that certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that technicians may use different nouns to refer to the same component. This specification and claims do not use the difference in nouns as a way to distinguish components, but use the difference in the functions of the components as the criterion for distinction. As mentioned throughout the specification and claims, "including" or "comprising" is an open term, so it should be interpreted as "including but not limited to". The subsequent description of the specification is a preferred embodiment of the present disclosure, but the description is based on the general principles of the specification and is not used to limit the scope of the present disclosure. The scope of protection of the present disclosure shall be determined by the attached claims.

[0022] To facilitate understanding of the embodiments of the present disclosure, further explanation will be given below using specific embodiments as examples in conjunction with the accompanying drawings, and each of the accompanying drawings does not constitute a limitation on the embodiments of the present disclosure.

[0023] Figure 1 is a flow chart of a low voltage compensation method for an autotransformer provided by an exemplary embodiment of the present disclosure, such as Figure 1 As shown, the method includes:

[0024] S100: Figure 2 As shown, under the condition that the compensating transformer and the autotransformer are integrated in the oil tank housing, the primary coil of the compensating transformer is connected to the voltage regulating coil of the autotransformer to form an excitation coil, and the secondary coil of the compensating transformer is connected in series with the low-voltage coil of the autotransformer, wherein the voltage regulating coil of the autotransformer is located in its three-phase series winding (such as Figure 3 As shown, A, B, and C represent the head end of the three-phase series winding of the autotransformer, and Ak, Bk, and Ck represent the end of the three-phase series winding of the autotransformer) and the three-phase common winding (such as Figure 3 The Am, Bm, and Cm shown in the figure represent the beginning of the three-phase common winding of the autotransformer, and the Xm, Ym, and Zm represent the end of the common winding of the autotransformer, respectively), and are close to the neutral point of the two windings ( Figure 3 O in the figure), the primary coil of the compensation coil (e.g. Figure 3 LC in the autotransformer) is connected in series with the voltage regulating coil of the autotransformer to form an excitation coil; the secondary coil of the supplementary transformer (for example Figure 3 BC in the autotransformer) is connected in series with the low-voltage coil of the autotransformer (the first end of the low-voltage coil of the autotransformer is connected by Figure 3 In the figure, a, b, and c represent respectively), the secondary coil of the compensation transformer is directly connected in series with these low-voltage coils, that is, one end of BC is connected to one of a, b, and c, and the other end is connected to the other end of the low-voltage side. In this way, the secondary voltage generated by the compensation transformer can be used to compensate for the changes in the low-voltage voltage of the autotransformer, ensuring that the low-voltage voltage is maintained at a stable level at different tap positions.

[0025] In this step, since the compensating transformer and the autotransformer are placed together in the same oil tank casing, it is easy to maintain and manage, and it can also ensure that the electrical connection between the two is more stable and reliable.

[0026] S200: Calculating the excitation voltage of the excitation coil of the autotransformer at different tap positions;

[0027] S300: Calculating the secondary side voltage of the secondary side coil of the compensation transformer at different tap positions of the autotransformer based on the excitation voltage of the excitation coil at different tap positions of the autotransformer;

[0028] S400: Calculate the low voltage of the autotransformer at different tap positions, and superimpose the calculated low voltage with the secondary side voltage of the secondary side coil of the compensation transformer at different tap positions of the autotransformer to compensate for the low voltage of the autotransformer.

[0029] In this embodiment, the autotransformer adjusts the output voltage of the transformer by changing the number of turns of the voltage regulating coil, so as to adapt to different load requirements. Its characteristic is that the voltage regulating coil is located at the neutral point of the series coil and the common coil. When the autotransformer switches gears, the voltage regulating coil is connected in series with different numbers of turns. At this time, the high-voltage and medium-voltage turns of the autotransformer will change, and the voltage of the low-voltage side that does not participate in the voltage regulation must remain constant. Therefore, at different gears, the potential of each turn will change, that is, the magnetic flux in the iron core will also change accordingly. This is the so-called variable flux voltage regulation.

[0030] Due to the change in potential per turn, the voltage of the low-voltage winding (usually called the third winding) with a constant number of turns will have serious deviations. This deviation may reach about 10%, which is unacceptable in many cases because it will cause the low-voltage side to be unable to carry load normally, affecting the normal operation of the equipment.

[0031] In summary, the voltage regulation of the autotransformer is usually achieved by changing the number of turns of the voltage regulating coil (i.e., the tap). The selection of the tap directly affects the voltage ratio between the high-voltage side and the low-voltage side. When the tap position changes, the electrical connection between the high-voltage side and the low-voltage side windings is actually changed, resulting in a change in the total number of turns ratio of the voltage regulating coil, thereby causing the excitation voltage generated by the excitation coil (the excitation voltage is caused by the magnetic flux generated between the high-voltage side and the low-voltage side after the power supply is applied to the high-voltage side of the autotransformer) to change accordingly, thereby causing the voltage on the secondary side of the compensation transformer to change accordingly (the compensation transformer generates the secondary side voltage through the mutual inductance between its primary side coil and the secondary side coil. Due to the transformation ratio of the compensation transformer, that is, the ratio of the primary side voltage to the secondary side voltage of the compensation transformer is fixed, therefore, if the voltage of the primary side coil (i.e., the excitation voltage) changes, the voltage induced in the secondary side coil will also change accordingly, that is, both increase or decrease at the same time), and superimposed on the low voltage of the autotransformer, thereby achieving compensation for the low voltage of the autotransformer. Through the above compensation method, even when the autotransformer is in different tap positions, its low voltage can be kept relatively stable, thereby ensuring the reliable operation of the power system.

[0032] In the following, this embodiment takes the OSSZ-240000 / 220 transformer as an example to specifically illustrate the above compensation method.

[0033] The voltage ratio of the OSSZ-240000 / 220 transformer is 220±4×1.25% / 115 / 10500KV, and the connection group is YNaod11. The number of low-voltage turns is 55, and the turn voltage et=10500 / 55=190.909KV. It can be calculated that the number of turns of the common winding is 317, the number of turns of the series winding is 348, and the number of turns of the voltage regulating winding is 36.

[0034] Specifically, compensating the low voltage of the OSSZ-240000 / 220 transformer specifically includes the following steps:

[0035] Step 1: Calculate the high voltage of the autotransformer at different tap positions;

[0036] In this step, when the autotransformer is in the 1-tap position, its high voltage is:

[0037] et1=115000 / (348-36) / 1.732=212.805KV

[0038] When the autotransformer is at the rated tap position, its high voltage is:

[0039] et5=115000 / 348 / 1.732=190.791KV

[0040] When the autotransformer is in the 9-tap position, its high voltage is:

[0041] et9=115000 / (348+36) / 1.732=172.904KV

[0042] In the above formula, 1.732 is a constant that represents the relationship between the line voltage and the phase voltage of the three-phase system. In a three-phase AC system, the voltage vector is distributed at an angle of 120 degrees, forming an equilateral triangle. According to the superposition principle of vectors, the line voltage (the voltage between two phase voltages) can be calculated by the vector sum of the phase voltages. For a balanced three-phase system, the line voltage V L and phase voltage V P The relationship between is expressed by the following formula:

[0043]

[0044] When calculating the high voltage of the autotransformer, this embodiment uses the value of 1.732, that is, , to convert from phase voltage to line voltage. This is because in actual three-phase transformer calculations, it is usually necessary to deal with line voltage, and the transformer nameplate data usually gives the line voltage.

[0045] Step 2: Calculate the low voltage of the autotransformer at different tap positions;

[0046] In this step, when the autotransformer is in the 1-tap position, its low voltage is:

[0047] V L1 =55*212.805=11704.275KV

[0048] When the autotransformer is at the rated tap position, its low voltage is:

[0049] V L5 =55*190.791=10493.505KV

[0050] When the autotransformer is in the 9-tap position, its low voltage is:

[0051] V L9 =55*172.904=9509.72KV

[0052] It can be seen that when the autotransformer is at the lowest tap position (i.e. 1 tap position) and the highest tap position (i.e. 9 tap position), its low voltage deviates greatly from the required 10500KV, which is approximately 11.47% and -9.43%. Therefore, the low voltage needs to be compensated, otherwise the low voltage cannot carry the load normally.

[0053] Step 3: Calculate the excitation voltage of the excitation coil of the autotransformer at different tap positions;

[0054] In this step, when the autotransformer is at the 1-tap position, the excitation voltage of the excitation coil is the product of the high voltage of the autotransformer at the 1-tap position and the number of turns of the voltage regulating winding of the autotransformer:

[0055] -36*212.805= -7660.98KV

[0056] When the autotransformer is at the 9-tap position, the excitation voltage of the excitation coil is the product of the high voltage voltage of the autotransformer at the 9-tap position and the number of turns of the voltage regulating winding of the autotransformer:

[0057] 36*172.904=6244.544KV

[0058] Step 4: Calculate the transformation ratio K of the compensation transformer:

[0059] In this step, when the autotransformer is at the 1st tap position, there are:

[0060] (55-(36 / K))*212.805=55*190.791

[0061] When the autotransformer is in the 9-tap position, there are:

[0062] (55+(36 / K))*172.904=55*190.791

[0063] By solving the above equations, we can obtain the transformation ratio K of the compensating transformer = 6.327.

[0064] Step 5: Calculate the secondary side voltage of the secondary side coil of the compensation transformer at different tap positions of the autotransformer;

[0065] In this step, when the autotransformer is at the 1-tap position, the secondary side voltage of the secondary side coil of the compensation transformer is the quotient of the excitation voltage of the excitation coil when the autotransformer is at the 1-tap position and the transformation ratio K:

[0066] V 补1 =-7660.98 / 6.327=-1210.84KV

[0067] When the autotransformer is at the 9-tap position, the secondary side voltage of the secondary side coil of the compensation transformer is the quotient of the excitation voltage of the excitation coil when the autotransformer is at the 9-tap position and the transformation ratio K:

[0068] V 补9 =6244.544 / 6.327=983.806KV

[0069] Step 6: superimposing the secondary side voltage of the secondary side coil of the compensation transformer at different tap positions of the autotransformer and the low voltage of the autotransformer at different tap positions.

[0070] In this step, when the autotransformer is at the 1st tap position, the low voltage after the autotransformer is compensated is:

[0071] 11704.275-1210.84=10493.435KV

[0072] When the autotransformer is at the 9-tap position, the low voltage after compensation by the autotransformer is:

[0073] 9509.72+983.806=10493.526KV

[0074] Through the above steps, it can be seen that the excitation coil generates different excitation voltages according to the different tap positions of the autotransformer voltage regulating coil. For the 1 tap position, the excitation voltage is -7660.98KV, and for the 9 tap position, the excitation voltage is 6244.544KV. These excitation voltages further determine the voltage on the secondary side of the compensation transformer, thereby achieving effective compensation for the low voltage and ensuring that the deviation of the low voltage is controlled within a reasonable range at different tap positions. Furthermore, the low voltages after compensation at the 1 tap position and the 9 tap position are 10493.435KV and 10493.526KV, respectively. Compared with the target value of 10500KV, the deviation is significantly reduced, from about 10% to -0.06%, which fully meets the load requirements.

[0075] In summary, the present disclosure forms an excitation coil by connecting the primary coil of the compensating transformer to the voltage regulating coil of the autotransformer, and connects the secondary coil of the compensating transformer to the low-voltage coil of the autotransformer in series, so that the appropriate compensation voltage can be calculated for different tap positions. This compensation mechanism can dynamically adjust the compensation amount according to the different tap positions of the autotransformer to ensure that the low voltage is maintained at a stable level, thereby solving the problem of high-low voltage ratio out-of-tolerance. In addition, when a short circuit occurs in the autotransformer, the voltage on the low-voltage side will be greatly impacted, resulting in an increased risk of equipment damage. By introducing a compensating transformer, additional voltage support can be provided in the case of a short circuit, so that the voltage on the low-voltage side does not drop too much. When the autotransformer is in different tap positions, the secondary voltage generated by the compensating transformer can be effectively superimposed on the low voltage, keeping the low voltage stable, reducing the damage to the equipment caused by voltage mutations, and thus improving the overall short-circuit resistance of the autotransformer. Therefore, the present invention not only improves the high-to-low voltage ratio out-of-tolerance problem of the traditional autotransformer by integrating the compensation transformer and connecting it to the autotransformer, but also enhances its stability when facing abnormal conditions in the power grid (such as short circuit), thereby ensuring the safe operation of the power system.

[0076] In another exemplary embodiment, the present disclosure further provides an autotransformer low-voltage compensation device, and the device applies the method described in any of the preceding items.

[0077] In another exemplary embodiment, the present disclosure further provides an autotransformer low-voltage compensation system, the system comprising the device as described above.

[0078] In another exemplary embodiment, the present disclosure further provides a storage medium, which includes instructions, which, when executed on a computer, enables the computer to execute a method as described in any of the preceding items, for example, under the conditions that the compensating transformer and the autotransformer are integrated in the oil tank housing, and the primary side coil of the compensating transformer is connected to the voltage regulating coil of the autotransformer to form an excitation coil, and the secondary side coil of the compensating transformer is connected in series with the low-voltage coil of the autotransformer, the excitation voltage of the excitation coil of the autotransformer at different tap positions is calculated; based on the excitation voltage of the excitation coil of the autotransformer at different tap positions, the secondary side voltage of the secondary side coil of the compensating transformer of the autotransformer at different tap positions is calculated; the low voltage of the autotransformer at different tap positions is calculated, and superimposed with the secondary side voltage of the secondary side coil of the compensating transformer at different tap positions of the autotransformer to compensate for the low voltage of the autotransformer.

[0079] In another exemplary embodiment, the present disclosure further provides an electronic device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the method described in any of the preceding items is implemented, for example, under the conditions that the compensating transformer and the autotransformer are integrated in the oil tank housing, and the primary side coil of the compensating transformer is connected to the voltage regulating coil of the autotransformer to form an excitation coil, and the secondary side coil of the compensating transformer is connected in series with the low-voltage coil of the autotransformer; calculating the excitation voltage of the excitation coil of the autotransformer at different tap positions; calculating the secondary side voltage of the secondary side coil of the compensating transformer at different tap positions of the autotransformer based on the excitation voltage of the excitation coil of the autotransformer at different tap positions; calculating the low voltage of the autotransformer at different tap positions, and superimposing it with the secondary side voltage of the secondary side coil of the compensating transformer at different tap positions of the autotransformer to compensate for the low voltage of the autotransformer.

[0080] The above embodiments are only for illustrating the technical concept and features of the present disclosure, and their purpose is to enable people familiar with the technology to understand the content of the present disclosure and implement it accordingly, and they cannot be used to limit the protection scope of the present disclosure. Any equivalent changes or modifications made according to the spirit of the present disclosure should be included in the protection scope of the present disclosure.

Claims

1. A method for compensating low voltage of an autotransformer, characterized in that: The method comprises: Under the condition that the compensating transformer and the autotransformer are integrated in the oil tank housing, the primary coil of the compensating transformer is connected to the voltage regulating coil of the autotransformer to form an excitation coil, and the secondary coil of the compensating transformer is connected in series with the low-voltage coil of the autotransformer, Calculating the excitation voltage of the excitation coil of the autotransformer at different tap positions; Calculating the secondary side voltage of the secondary side coil of the compensation transformer at different tap positions of the autotransformer based on the excitation voltage of the excitation coil at different tap positions of the autotransformer; The low voltage of the autotransformer at different tap positions is calculated and superimposed with the secondary side voltage of the secondary side coil of the compensation transformer at different tap positions of the autotransformer to compensate for the low voltage of the autotransformer.

2. The method according to claim 1, characterized in that Preferably, calculating the excitation voltage of the excitation coil of the autotransformer at different tap positions comprises the following steps: Calculating the high voltage voltage of the autotransformer at different tap positions; The excitation voltage of the excitation coil of the autotransformer at different tap positions is calculated based on the high voltage of the autotransformer at different tap positions and the number of turns of the voltage regulating winding of the autotransformer.

3. The method according to claim 1, characterized in that: The method comprises the following steps: calculating the secondary side voltage of the secondary side coil of the compensation transformer based on the excitation voltage of the excitation coil of the autotransformer at different tap positions; Calculating the transformation ratio of the compensating transformer; The secondary side voltage of the secondary side coil of the compensating transformer at different tap positions of the autotransformer is calculated based on the transformation ratio of the compensating transformer and the excitation voltage of the excitation coil of the autotransformer at different tap positions.

4. A low voltage compensation device for an autotransformer, characterized in that: The device applies the method according to any one of claims 1 to 3.

5. An autotransformer low voltage compensation system, characterized in that: The system comprises the apparatus of claim 4.

6. A storage medium, characterized in that: The method comprises instructions, which, when executed on a computer, enable the computer to execute the method according to any one of claims 1 to 3.

7. An electronic device, characterized in that: The electronic device comprises: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the method according to any one of claims 1 to 3 is implemented.

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