Differential protection method and system for symmetric double-core phase-shifting transformer body

Abstract

The invention relates to the technical field of flexible interconnection of a power distribution network, in particular to a differential protection method and system for a symmetric dual-core phase-shifting transformer body. On the basis of common magnetic balance differential and electric balance differential in a common power transformer, a set of electric balance differential protection scheme and two sets of magnetic balance differential protection schemes are configured according to the structural characteristics of a double-core symmetrical phase-shifting transformer. For a transformer with a tap, as rated voltage parameters set in a relay protection device cannot be automatically adjusted, unbalanced current can be generated in differential protection calculation. The new body protection method corrects the unbalanced current, and then the corrected current is subjected to protection setting. And a self-adaptive adjustment strategy is provided for differential current in electric balance and magnetic balance, so that the protection range is more accurate. The safety and reliability of a power system are improved, and the stability of the system during operation is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of flexible interconnection of distribution networks, and in particular to a method and system for differential protection of a symmetrical double-core phase-shifting transformer body. Background Art

[0002] The distribution network is the power cornerstone of social and economic operations, and it is crucial to ensure efficient power supply and stable operation. However, the current distribution network is facing multiple challenges: on the one hand, a large number of diversified loads with randomness and volatility, as well as the widespread access of distributed power sources, have brought problems of reduced power quality and power supply reliability to the distribution network. On the other hand, as power users continue to increase their requirements for power supply reliability and stability, the distribution network needs to meet higher service standards. In response to the above problems, relevant scholars at home and abroad have conducted research on new modes of distribution network operation. The flexible interconnection technology of the distribution network can not only realize interconnection and transfer, but also realize power flow regulation, which is an important direction for the development of technology in this field.

[0003] The flexible interconnection technology scheme for distribution networks of single-core, double-core, symmetrical and asymmetrical phase-shifting transformers is considered to be a flexible interconnection technology with wide application value due to its advantages of high reliability, good stability and good regulation effect. However, for common tapped transformers, because the rated voltage parameters set in the relay protection device will not be adjusted automatically, a fixed transformation ratio is usually used for calculation, so unbalanced current will be generated in the calculation of differential protection. The normal tap offset range of the phase-shifting transformer is small, and the differential current amplitude generated by the gear adjustment is also small. The differential starting setting and proportional braking characteristics can usually be used to prevent protection from malfunction. However, there is a parallel voltage-regulating transformer in the phase-shifting transformer, which can be adjusted from the middle gear to the full gear of positive and negative polarity. Therefore, if a fixed rated voltage parameter is used, the differential current calculated by the differential protection at different gears has a large deviation, and the ratio braking characteristic cannot reliably brake the protection, which makes the transformer protection have the risk of malfunction. Therefore, a new relay protection method is needed to realize the adaptive adjustment of differential protection. Summary of the invention

[0004] In view of the above problems existing in the prior art, the present invention is proposed.

[0005] Therefore, the purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a symmetrical double-core phase-shifting transformer body differential protection method to achieve adaptive adjustment of differential current.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: a symmetrical double-core phase-shifting transformer body differential protection method, comprising: installing a current transformer according to the topological structure of the phase-shifting transformer, the current transformer receiving and feeding back the current magnitude;

[0007] Formulate adaptive protection schemes according to gear changes and correct the current;

[0008] Configure the electrically balanced differential and magnetically balanced differential protection schemes and conduct experiments based on the corrected current to determine whether the protection method is applicable.

[0009] As a preferred solution of the differential protection method for a symmetrical double-core phase-shifting transformer body described in the present invention, the topological structure of the phase-shifting transformer is a tapped structure, and the double-core symmetrical phase-shifting transformer comprises a series transformer and a parallel transformer.

[0010] As a preferred scheme of the differential protection method of a symmetrical double-core phase-shifting transformer body described in the present invention, wherein: the double-core symmetrical phase-shifting transformer means that the voltage regulation function of the phase-shifting transformer is completed by two transformers; the symmetrical type means that while ensuring that the voltage and current amplitudes on the input side and the output side of the phase-shifting transformer are the same, the phases of the voltage and current on both sides are changed, and the voltage and current phase changes are the same.

[0011] As a preferred solution of the differential protection method for a symmetrical double-core phase-shifting transformer body described in the present invention, the neutral point of the symmetrical double-core phase-shifting transformer is grounded, and the excitation part and the system are not directly connected.

[0012] As a preferred scheme of the differential protection method for the main body of a symmetrical double-core phase-shifting transformer described in the present invention, the symmetrical double-core phase-shifting transformer requires an electric balance protection KD1, KD1 is a differential protection based on the current balance of the T-connected winding on the primary side of the series transformer, reflecting the grounding and phase-to-phase faults of the primary side winding of the series transformer.

[0013] As a preferred solution of the differential protection method for a symmetrical double-core phase-shifting transformer body described in the present invention, the voltage regulation function of the symmetrical double-core phase-shifting transformer is completed by two transformers, and two sets of magnetic balance protection KD2 and KD3 are required to protect the two transformers respectively.

[0014] As a preferred solution of the differential protection method of a symmetrical double-core phase-shifting transformer body described in the present invention, wherein: for the parallel voltage-regulating transformer in the phase-shifting transformer, the gear is adjusted from the middle to the full gear of the positive and negative polarities. Let the middle gear be X, that is, when running to the X gear, the output voltage of the gear-adjusting side is zero, and then the rated voltage coefficient and the correction balance coefficient are calculated, and then the differential protection calculation is performed using the corrected adjustment current.

[0015] As a preferred solution of a symmetrical double-core phase-shifting transformer body differential protection system described in the present invention, it includes: a symmetrical double-core phase-shifting transformer 100, a plurality of current transformers CT200 at different positions, a phase-shifting transformer tap control module 300, and a protection module 400, characterized in that: the current transformer CT200 is used to collect the current magnitude on both sides of the symmetrical double-core phase-shifting transformer 100, and send it to the phase-shifting transformer tap control module 300 and the protection module 400;

[0016] After receiving the collected current, the phase-shifting transformer tap control module 300 calculates the protection differential threshold according to the gear adjustment of its own tap and the current after the gear adjustment, based on the new body protection method. The protection module 400 makes a judgment based on the current transmitted by the current transformer CT200. If the current is greater than the set threshold, the protection module 400 sends a cut-off signal and the protection starts to work.

[0017] A computer device comprises a memory and a processor, wherein the memory stores a computer program, and is characterized in that when the processor executes the computer program, the steps of any one of the methods for differential protection of a symmetrical double-core phase-shifting transformer body are implemented.

[0018] A computer-readable storage medium having a computer program stored thereon, characterized in that when the computer program is executed by a processor, the steps of any one of the methods for differential protection of a symmetrical double-core phase-shifting transformer body are implemented.

[0019] The beneficial effects of the present invention are as follows: First, the present invention calculates the rated voltage coefficient and the correction balance coefficient according to the phase-shifting transformer tap. The corrected adjustment current is used to perform differential protection calculations. Finally, the calculation results are substituted into the protection setting and verification. For common tapped transformers, the normal tap offset range of the phase-shifting transformer is small, and the differential current amplitude generated by the gear adjustment is also small. The differential starting setting and proportional braking characteristics can usually be used to prevent the protection from malfunctioning. However, there is a parallel voltage-regulating transformer in the phase-shifting transformer, which can be adjusted from the middle gear to the full gear of positive and negative polarity. If a fixed rated voltage parameter is used, the differential current calculated by the differential protection at different gears will have a large deviation, and the ratio braking characteristic cannot reliably brake the protection. The new method reduces the risk of false operation of the transformer.

[0020] Secondly, the present invention reduces the unbalanced current in the phase-shifting transformer by coefficient correction. Because the rated voltage parameters set in the relay protection device will not be automatically adjusted, and usually a fixed transformation ratio is used for calculation, unbalanced current will be generated in the calculation of differential protection.

[0021] Thirdly, compared with the conventional phase-shifting transformer electric balance and magnetic balance protection schemes, this method has higher protection accuracy and reliability. It is also highly practical and has wide promotion value and engineering application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0023] Figure 1 A phase-shifting transformer protection control flow chart of a symmetrical double-core phase-shifting transformer body differential protection method provided by one embodiment of the present invention;

[0024] Figure 2 A structural diagram of a symmetrical double-core phase-shifting transformer for a method for differential protection of a symmetrical double-core phase-shifting transformer body provided by one embodiment of the present invention;

[0025] Figure 3 A three-phase structure diagram of a symmetrical double-core phase-shifting transformer for a method for differential protection of a symmetrical double-core phase-shifting transformer provided by an embodiment of the present invention;

[0026] Figure 4 A transformer configuration of a symmetrical double-core phase-shifting transformer for a symmetrical double-core phase-shifting transformer body differential protection method provided by an embodiment of the present invention;

[0027] Figure 5 An electric balance protection configuration of a symmetrical double-core phase-shifting transformer of a symmetrical double-core phase-shifting transformer body differential protection method provided by an embodiment of the present invention;

[0028] Figure 6 A magnetic balance protection configuration of a symmetrical double-core phase-shifting transformer is provided in a method for differential protection of a symmetrical double-core phase-shifting transformer body according to an embodiment of the present invention. DETAILED DESCRIPTION

[0029] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0030] Example 1

[0031] Reference Figure 1-Figure 6 , is the first embodiment of the present invention, which provides a symmetrical double-core phase-shifting transformer body differential protection method, which is greatly improved compared with the prior art and has more reliable protection. Figure 1 As shown, including:

[0032] A method for differential protection of the body of a symmetrical double-core phase-shifting transformer is characterized in that, based on the common magnetic balance differential and electric balance differential in ordinary power transformers, according to the structural characteristics of the double-core symmetrical phase-shifting transformer itself, a set of electric balance differential and two sets of magnetic balance differential protection schemes are configured to comprehensively protect all parts of the phase-shifting transformer and improve the safety and reliability of the system. An adaptive adjustment strategy is proposed for the differential current in the electric balance and magnetic balance to make the protection range more accurate. The theoretical analysis and simulation experiments are used to verify whether the body differential protection range and coordination are established.

[0033] S1. Install the current transformer (CT) according to the topology of the phase-shifting transformer, and the CT receives and feeds back the current. The differential protection configuration and protection range are also set according to the different CT installation locations.

[0034] like Figure 4 As shown in the figure, the protection range of the series transformer longitudinal differential is bounded by CT2, CT3 and CT9, including the secondary windings of the series transformer and the parallel transformer; the protection range of the series transformer phase differential is bounded by CT2, CT3 and CT5, excluding the series transformer angle side outgoing line. The protection range of the parallel transformer longitudinal differential is bounded by CT6 and CT9, including the parallel transformer winding part. The various protection parts work together to fully protect all parts of the phase-shifting transformer, which improves the safety of system protection.

[0035] It should be noted that the secondary winding of the phase-shifting transformer is a tapped structure, and the double-core symmetrical phase-shifting transformer is mainly composed of a series transformer and a parallel transformer (also called an excitation transformer).

[0036] It should be noted that "double-core type" means that the voltage regulation function of the phase-shifting transformer is completed by two transformers; "symmetrical type" means that the voltage (current) amplitude on the input side and the output side of the phase-shifting transformer is the same, and the phase changes of the voltage (current) on both sides are changed, and the voltage and current phase changes are the same. In addition, the neutral point of the symmetrical double-core phase-shifting transformer is grounded, and the excitation part and the system are not directly connected. With its unique structural advantages, the closed-loop voltage can be minimized. Reduce the possibility of failure.

[0037] S2, such as Figure 2The figure shows the structure of a symmetrical dual-core phase-shifting transformer with a tap position control module. For common phase-shifting transformers with taps, unbalanced current will be generated during differential protection calculation, resulting in a large deviation in the differential current calculated by differential protection. Therefore, a new adaptive protection scheme is formulated according to the position change to correct the current. This reduces engineering errors in the actual working process and improves protection accuracy and reliability.

[0038] After receiving the collected current, the phase-shifting transformer tap control module first adjusts the gear position of its own tap, then combines the current size after the gear position correction, and calculates the threshold of the protection differential according to the new body protection method. The protection module makes a judgment based on the current size transmitted by the current transformer CT. If the current is greater than the set threshold, the protection module sends a cut-off signal.

[0039] S3, one set of electrically balanced differential and two sets of magnetically balanced differential protection schemes are configured to conduct experiments based on the corrected current to determine whether the protection method is perfectly applicable.

[0040] It should be noted that by analyzing the magnetic circuit structure of the phase-shifting transformer, a symmetrical double-core phase-shifting transformer differential protection method is designed and proposed based on basic circuit principles such as Kirchhoff's current law and the law of electromagnetic induction. This method is suitable for double-core structures and is more effective than conventional methods. It can effectively respond to various internal faults of the phase-shifting transformer.

[0041] Furthermore, the symmetrical double-core phase-shifting transformer requires a set of electric balance protection KD1. KD1 is a differential protection based on the current balance of the primary "T"-connected winding of the series transformer, which is used to reflect the grounding and phase-to-phase faults of the primary winding of the series transformer.

[0042] Furthermore, the voltage regulation function of the symmetrical double-core phase-shifting transformer is completed by two transformers, so two sets of magnetic balance protection KD2 and KD3 are required to protect the two transformers respectively. The principle of the series transformer magnetic balance KD2 is similar to that of the Y / Y / D type connection transformer, and the principle of the excitation variable magnetic balance KD3 is similar to that of the Y / Y type connection transformer. The cooperation of KD1, KD2, and KD3 can make the protection more comprehensive. This solution is highly practical and has a wide range of promotion value and engineering application value.

[0043] Specifically, the principle of electrical balance protection is as follows:

[0044] like Figure 3 , Figure 4 and Figure 5 As shown, according to the flux balance relationship of the series transformer, the current relationship equation on both sides of the series transformer is written:

[0045]

[0046] Among them, taking phase A as an example, and are the currents at the S and L terminals of the series transformer series side of the phase-shifting transformer respectively; i SA2 is the current on the series transformer side. Similarly, the currents on the B-phase and C-phase sides are only different from those on the A-phase side in terms of marking. This description will not be repeated later. ST is the transformation ratio of the phase-shifting transformer.

[0047] It should be noted that, taking phase A as an example, the current relationship equation between the secondary side of the series transformer and the secondary side of the excitation transformer can be listed as follows:

[0048]

[0049] It should be noted that, considering that the primary side of the series transformer and the primary side of the excitation transformer have a direct circuit connection, according to Kirchhoff's current law, taking phase A as an example, the current relationship equation between the primary side of the series transformer and the primary side of the excitation transformer is listed:

[0050]

[0051] where n ST is the tap ratio.

[0052] Furthermore, the expression for the differential current is as follows:

[0053]

[0054] in, The three differential currents are normally zero. If they are not zero, it means that unbalanced current occurs and the protection will be activated.

[0055] Specifically, the principle of magnetic balance protection is as follows:

[0056] like Figure 3 , Figure 4 and Figure 6 As shown, according to the flux balance relationship of the series transformer, the expression equation of the differential current is written as:

[0057]

[0058] It should be noted that for common tapped transformers, unbalanced current will be generated in the calculation of differential protection because the rated voltage parameters set in the relay protection device will not be adjusted automatically. The new body protection method corrects the unbalanced current and then sets the protection for the corrected current.

[0059] It should be noted that the cooperation between the protection device and the control device can obtain the operating gear and gear status information of the tap changer on the parallel variable speed side of the phase-shifting transformer in real time.

[0060] It should be noted that for the parallel voltage-regulating transformer in the phase-shifting transformer, its gear can be adjusted from the middle to the full gear of the positive and negative polarities. Let the current gear be gear x, and let the middle gear be X. That is, when running to gear X, the output voltage of the gear-adjusting side is zero, x∈[1,2X-1], and x is an integer. When x is less than X, it runs to the reverse gear, and when x is greater than X, it runs to the forward gear.

[0061] Calculate the rated voltage coefficient k at the x position on the shift side x The formula is:

[0062]

[0063] Among them: U x U is the rated voltage when the gear is in gear x on the gear shifting side; N is the rated voltage of the gear-adjusting side at 2X-1 gear. When x=X, that is, in the middle gear, the rated voltage of the gear-adjusting side is U x =0kV.

[0064] Calculate the rated current of each side of the parallel transformer at 2X-1 level. pri and I tap , and the balance coefficients on each side are K pri and K tap .

[0065] Calculate the correction balance coefficient K of the parallel transformer secondary side at position m tap.x

[0066] K tap.x =sgn(xX)·k x ·K tap

[0067] When x>X, sgn(xX)=1; when X>x, sgn(xX)=-1; when m=M, sgn(xX)=0.

[0068] Furthermore, when the parallel tap changer is operated to position x, the balance coefficient on the non-voltage regulating side is still K pri , the balance coefficient of the pressure regulating side adopts the correction balance. The coefficient is K tap.x , thus the corrected adjustment current on each side of the voltage regulating transformer under the current x gear can be calculated, and then the corrected adjustment current can be used for differential protection calculation.

[0069] Furthermore, during the gear adjustment process, the received gear position and the actual gear position of the phase-shifting transformer may be inconsistent, so it is necessary to set a high starting value, add an insensitive segment longitudinal difference on the basis of the parallel transformer longitudinal difference, and appropriately increase the slope of the braking characteristic curve.

[0070] Furthermore, when the protection device receives a signal that the gear is being adjusted, the parallel transformer longitudinal difference can be switched to an insensitive section, and the series transformer longitudinal difference and the phase difference are not affected by the gear adjustment and are calculated in the conventional way; the winding difference based on the electrical balance principle is also not affected by the gear adjustment.

[0071] Therefore, when the phase-shifting transformer is in normal operation or out-of-zone fault, it avoids the maximum unbalanced current, and the action threshold is as follows:

[0072] I set =K tap.x ·K rel (K er +Δm)·I e

[0073] In the formula, K rel is the reliability coefficient, which is 1.3-1.5; K er is the maximum relative error allowed by the current transformer, which is set to 0.1. Δm is the error caused by the incomplete matching of the current transformer ratio, which is set to 0.05 in the initial setting; I e It is the rated current of the primary side of the series transformer.

[0074] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

[0075] Example 2

[0076] The second embodiment of the present invention provides a symmetrical double-core phase-shifting transformer body differential protection system, which is characterized by comprising a symmetrical double-core phase-shifting transformer, a plurality of current transformers CT at different positions, a phase-shifting transformer tap control module, and a protection module.

[0077] The current transformer CT is used to collect the current magnitudes on both sides of the symmetrical double-core phase-shifting transformer, and then send them to the phase-shifting transformer tap control module and protection module;

[0078] After receiving the collected current, the phase-shifting transformer tap control module first adjusts the gear position of its own tap, and then calculates the protection differential threshold according to the new body protection method based on the current size after the gear position correction. The protection module makes a judgment based on the current size transmitted by the current transformer CT. If the current is greater than the set threshold, the protection module sends a cut-off signal and the protection starts to work.

[0079] If the protection module detects that the quality of the gear signal does not meet the standard, it will immediately stop the differential protection function of the parallel transformer and issue a warning message of abnormal gear information. At the same time, the protection device will pass this abnormal information to the control module. Once the control module receives the gear information abnormality signal or communication link failure signal from the protection device, it will immediately disable the gear adjustment function of the phase-shifting transformer and take measures to gradually stop the operation of the phase-shifting transformer. At the same time, the current difference calculated by the differential adaptive adjustment technology can be continuously maintained at a low level during the normal operation of the phase-shifting transformer.

[0080] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc., which can store program codes.

[0081] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in conjunction with such instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in conjunction with such instruction execution systems, devices or apparatuses.

[0082] More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic device), a portable computer disk case (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be a paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, deciphering or, if necessary, processing in another suitable manner, and then stored in a computer memory.

[0083] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0084] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A symmetrical double-core phase-shifting transformer body differential protection method, characterized in that: include, A current transformer is installed according to the topological structure of the phase-shifting transformer, and the current transformer receives and feeds back the current magnitude; Formulate adaptive protection schemes according to gear changes and correct the current; Configure the electrically balanced differential and magnetically balanced differential protection schemes and conduct experiments based on the corrected current to determine whether the protection method is applicable.

2. A symmetrical double-core phase-shifting transformer body differential protection method as claimed in claim 1, characterized in that: The phase-shifting transformer topology structure is a tapped structure, and the double-core symmetrical phase-shifting transformer comprises a series transformer and a parallel transformer.

3. A method for differential protection of a symmetrical double-core phase-shifting transformer as claimed in claim 2, characterized in that: The dual-core symmetrical phase-shifting transformer means that the voltage regulation function of the phase-shifting transformer is completed by two transformers; the symmetrical type means that while ensuring that the voltage and current amplitudes on the input side and the output side of the phase-shifting transformer are the same, the phases of the voltage and current on both sides are changed, and the voltage and current phase changes are the same.

4. A method for differential protection of a symmetrical double-core phase-shifting transformer as claimed in claim 3, characterized in that: The neutral point of the symmetrical double-core phase-shifting transformer is grounded, and the excitation part is not directly connected to the system.

5. A method for differential protection of a symmetrical double-core phase-shifting transformer as claimed in claim 4, characterized in that: Symmetrical double-core phase-shifting transformers require electric balance protection KD1. KD1 is a differential protection based on the current balance of the primary T-connected winding of the series transformer, reflecting the grounding and phase-to-phase faults of the primary winding of the series transformer.

6. A method for differential protection of a symmetrical double-core phase-shifting transformer as claimed in claim 5, characterized in that: The voltage regulation function of the symmetrical double-core phase-shifting transformer is completed by two transformers, and two sets of magnetic balance protection KD2 and KD3 are required to protect the two transformers respectively.

7. A method for differential protection of a symmetrical double-core phase-shifting transformer as claimed in claim 6, characterized in that: For the parallel voltage regulating transformer in the phase-shifting transformer, the gear is adjusted from the middle to the full gear of positive and negative polarity. Let the middle gear be X, that is, when it runs to gear X, the output voltage on the gear-adjusting side is zero, and then the rated voltage coefficient and the correction balance coefficient are calculated, and then the differential protection calculation is performed using the corrected adjustment current.

8. A symmetrical double-core phase-shifting transformer body differential protection system, comprising a symmetrical double-core phase-shifting transformer (100), a plurality of current transformers (CTs) at different positions (200), a phase-shifting transformer tap control module (300), and a protection module (400), characterized in that: The current transformer CT (200) is used to collect the current magnitudes on both sides of the symmetrical double-core phase-shifting transformer (100), and send the current magnitudes to the phase-shifting transformer tap control module (300) and the protection module (400); After receiving the collected current magnitude, the phase-shifting transformer tap control module (300) calculates the threshold value of the protection differential according to the gear situation of its own tap adjustment and the current magnitude after the gear situation correction according to the novel body protection method. The protection module (400) makes a judgment according to the current magnitude transmitted by the current transformer CT (200). If the current is greater than the set threshold value, the protection module (400) sends a cut-off signal and the protection starts to act.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

Images