Main protection optimization design method and system for odd-number multi-branch wave winding generator

Abstract

The invention relates to the technical field of relay protection of electrical main equipment, in particular to a main protection optimization design method and system for an odd-number multi-branch wave winding generator. An enumeration method is adopted to count actual internal faults of the generator; analyzing and calculating the generated internal fault by using a multi-loop analysis method; recommending a generator main protection configuration scheme through a generator main protection quantitative design process; a shaped copper ring leading-out mode on the neutral point side of an odd number of multi-branch wave winding generator and a branch group electromagnetic TA are reserved, flexible optical TA is wound on a branch according to a quantitative design result of main protection of the generator, a main protection scheme is added through combined arrangement of the flexible optical TA and the electromagnetic TA, and the main protection scheme is optimized. While a main protection configuration scheme is optimized to reduce protection dead zones, analysis and judgment of the generator to deal with eccentric vibration accidents are improved. Through flexible winding of the flexible optical TA and optimal design of main protection, a protection dead zone of turn-to-turn / inter-phase short circuit with a small number of turns is eliminated.

Description

Technical Field

[0001] The invention relates to the technical field of relay protection of electrical main equipment, and in particular to a main protection optimization design method and system for an odd-number multi-branch wave winding generator. Background Art

[0002] The quantitative design method of generator main protection based on internal fault analysis ("multi-loop analysis method") has been promoted and applied in the hydropower field. On the basis of comprehensive simulation calculation of generator internal faults using the "multi-loop analysis method", different quantitative and optimization design processes are proposed according to the generator winding structure and the number of branches per phase. This has opened up a new way to scientifically formulate the generator main protection configuration plan, reasonably select the generator neutral point side branch lead-out method and the electromagnetic TA configuration plan.

[0003] In engineering practice, for odd-numbered multi-branch wave winding generators (a=7 / 9 / 11), the design of their main protection configuration schemes tends to be based on how to use incomplete split-phase differential protection (that is, according to the actual fault characteristics of the generator, abandon a certain branch of each phase while realizing the reasonable grouping of the remaining even-numbered branches - adjacent or separated). The advantage of this is that it has high sensitivity to short-circuit between turns of the same branch with a small number of turns, and small unbalanced current when the TAs on both sides of the differential protection are completely of the same type / out-of-zone faults.

[0004] However, it also increases the difficulty of neutral point lead-out and copper ring arrangement of the generator, especially it is difficult to install a small ratio electromagnetic TA (whose volume is larger) on the branch abandoned by the incomplete phase-split differential protection, resulting in a small turn phase-to-phase short circuit on the neutral point side between the three-phase abandoned branches becoming a protection dead zone. At the same time, since the phase current on the neutral point side of the generator cannot be obtained (the "-1-" branch is not equipped with a TA), complete longitudinal differential protection cannot be achieved. When the generator vibrates eccentrically, it is impossible to make effective auxiliary judgments based on the different action behaviors of the transverse differential and complete longitudinal differential protections. Summary of the invention

[0005] In view of the above problems existing in the prior art, the present invention is proposed.

[0006] Therefore, in order to overcome the above difficulties, it is necessary to study the optimization design method of the main protection of the odd-numbered multi-branch wave winding generator. With the advantage of the flexible winding of the flexible optical TA, without increasing the difficulty of the branch grouping on the neutral point side of the generator, the copper ring lead-out method and the electromagnetic branch group TA arrangement, the main protection configuration scheme is optimized to reduce the protection dead zone and improve the analysis and judgment of the generator in response to eccentric vibration accidents, thereby eliminating the operating safety hazards of the odd-numbered multi-branch wave winding generator.

[0007] The present invention provides the following technical solution, a method for optimizing the design of main protection of an odd-number multi-branch wave winding generator, comprising: using an enumeration method to count actual internal faults occurring in the generator;

[0008] Use multi-loop analysis method to analyze and calculate the internal faults that occur;

[0009] Recommend the generator main protection configuration scheme through the quantitative design process of generator main protection;

[0010] The established copper ring lead-out method and branch group electromagnetic TA on the neutral point side of the odd-numbered multi-branch wave winding generator are retained. According to the quantitative design results of the generator main protection, a flexible optical TA is wound on a specific branch. The main protection scheme is added through the combined arrangement of a flexible optical TA and an electromagnetic TA. While optimizing the main protection configuration scheme to reduce the protection dead zone, the analysis and judgment of the generator in response to eccentric vibration accidents is improved.

[0011] As a preferred scheme of the main protection optimization design method of the odd-numbered multi-branch wave winding generator described in the present invention, the internal faults include the number and distribution characteristics of short circuits between turns of the same branch, short circuits between turns of the same phase but different branches, and short circuits between phases.

[0012] As a preferred scheme of the main protection optimization design method of the odd-numbered multi-branch wave winding generator described in the present invention, the analysis and calculation include: inputting the original data items, calculating the inductance coefficient of each stator coil generated by the air gap magnetic field, calculating the inductance coefficient of each stator coil generated by the end leakage magnetic field, calculating the resistance of each stator branch, calculating the self-inductance of the excitation circuit, calculating the inductance coefficient of the excitation circuit and each stator branch, calculating the inductance coefficient of the excitation circuit and each damping circuit, calculating the inductance coefficient of each damping, calculating the inductance coefficient of each damping circuit and each stator branch, forming a state equation according to the fault state, solving it, and outputting the final result.

[0013] As a preferred solution of the method for optimizing the main protection of an odd-numbered multi-branch wave winding generator described in the present invention, the quantitative design process includes initialization conditions, calling a generator fault type analysis subroutine, counting the number and type of internal faults actually occurring in the generator, calling a generator internal fault simulation calculation subroutine based on a multi-loop analysis method, calculating the performance indicators of various main protection schemes, and determining the lead-out method on the neutral point side of the generator from the type of transverse differential protection. If the performance of the zero-sequence current type transverse differential protection is better than that of the split-phase transverse differential protection, the zero-sequence current type transverse differential protection is selected, and the neutral point of the generator is led out in a corresponding manner. Otherwise, the split-phase transverse differential protection is selected, and only one neutral point is led out. The longitudinal differential protection is added to form a preliminary pattern of "one horizontal and one vertical", and the number and position of the branch TA are determined to determine whether the preliminary pattern meets the design requirements. If the design requirements are met, it is the final main protection configuration scheme for power generation. If the design requirements are not met, the trade-offs and composition methods of the transverse differential and longitudinal differential protections are considered on the basis of quantitative analysis until the design indicators are met.

[0014]

[0015] Where N represents the type of main protection scheme, F Ai It is represented by the number of faults that a certain main protection scheme cannot operate, n is represented by the number of internal faults actually occurring in the generator, ε 1 Expressed as a design target, i.e., the size of the protection dead zone (in percentage).

[0016] As a preferred scheme of the main protection optimization design method for the odd-numbered multi-branch wave winding generator described in the present invention, the analysis and judgment includes: a quantitative design scheme for the main protection of the multi-branch stacked winding generator, whether the protection dead zone of the existing generator main protection configuration scheme is a small turn-to-turn or phase-to-phase short circuit on the branch without the electromagnetic TA or between the branches; if not installed, a flexible optical TA is wound on the branch without the electromagnetic TA, and a corresponding main protection scheme is added to eliminate the protection dead zone for the small turn-to-turn or phase-to-phase short circuit; if installed, the final main protection configuration scheme of the generator has the smallest dead zone and is helpful for the analysis and judgment of the rotor eccentric vibration.

[0017] As a preferred scheme of the method for optimizing the main protection of an odd-numbered multi-branch wave winding generator described in the present invention, the quantitative design results of the main protection of the generator include two sets of zero-sequence current type differential protection, one set of incomplete split-phase differential protection and two sets of incomplete longitudinal differential protection.

[0018] As a preferred scheme of the main protection optimization design method for the odd-numbered multi-branch wave winding generator described in the present invention, wherein: the main protection scheme includes a set of incomplete phase-split transverse differential protection, a set of incomplete longitudinal differential protection and a set of complete longitudinal differential protection. The main protection configuration scheme is simple and helps to improve the performance of the microcomputer protection device.

[0019] As a preferred solution of the main protection optimization design system for the odd-number multi-branch wave winding generator described in the present invention, it includes: a fault enumeration analysis module, a loop analysis and calculation module, a main protection design module, and a protection scheme optimization module;

[0020] The fault enumeration analysis module uses the enumeration method to count the actual internal faults of the generator;

[0021] The loop analysis and calculation module uses the multi-loop analysis method to analyze and calculate the internal faults that occur;

[0022] The main protection design module recommends the configuration scheme of the main protection of the generator through the quantitative design process of the main protection of the generator;

[0023] The protection scheme optimization module retains the established copper ring lead-out method and branch group electromagnetic TA on the neutral point side of the odd-numbered multi-branch wave winding generator. According to the quantitative design results of the generator main protection, a flexible optical TA is wound on the branch. The main protection scheme is added through the combination of flexible optical TA and electromagnetic TA. While optimizing the main protection configuration scheme to reduce the protection dead zone, the analysis and judgment of the generator in response to eccentric vibration accidents is improved.

[0024] 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 optimizing the design of main protection of an odd-numbered multi-branch wave winding generator are implemented.

[0025] 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 optimizing the design of main protection of an odd-numbered multi-branch wave winding generator are implemented.

[0026] The beneficial effects of the present invention are as follows: on the basis of using the "multi-loop analysis method" to fully simulate and calculate the internal faults of the generator, based on the branch grouping method (3-1-3 or 4-1-4 or 5-1-5) of the existing odd-numbered multi-branch wave winding generator (a=7 / 9 / 11) and the layout of the electromagnetic branch group TA and the type of inoperable fault, a flexible optical TA is "targeted" on the "-1-" branch, and incomplete longitudinal differential protection and corresponding complete longitudinal differential protection of the flexible optical TA connected to the neutral point side are added. Under the premise of not changing the branch grouping on the neutral point side of the generator, the copper ring lead-out method and the layout of the electromagnetic branch group TA, the protection dead zone for small-turn inter-turn / inter-phase short circuits is eliminated through the flexible winding of the flexible optical TA and the optimized design of the main protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] 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.

[0028] Figure 1 This is a block diagram for analyzing generator fault types in the present invention.

[0029] Figure 2 This is a simulation calculation block diagram of the generator internal fault based on the multi-loop analysis method in the present invention.

[0030] Figure 3 This is a flow chart for the quantitative design of main protection for large and medium-sized generators in the present invention.

[0031] Figure 4 It is a schematic diagram of the optimization design of the internal fault main protection and TA configuration of the odd-numbered multi-branch wave winding generator in the present invention.

[0032] Figure 5 This is a flow chart for optimizing the design of main protection for an odd-numbered multi-branch wave winding generator in the present invention.

[0033] Figure 6 It is a schematic diagram of a small-turn phase-to-phase short circuit on the neutral point side occurring between branches of the Xiangjiaba ALSTOM generator not equipped with an electromagnetic TA in the present invention.

[0034] Figure 7 It is a schematic diagram of the influence of rotor eccentricity on the balance of concentrated winding branches and the complete longitudinal differential protection performance in the present invention.

[0035] Figure 8 It is a schematic diagram of the internal fault main protection and TA configuration optimization design scheme of the Xiangjiaba ALSTOM generator in the present invention. DETAILED DESCRIPTION

[0036] 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.

[0037] Example 1

[0038] Reference Figure 1-Figure 5 , which is the first embodiment of the present invention, and provides an optimization design method for the main protection of an odd-number multi-branch wave winding generator, such as Figure 1 As shown, including:

[0039] The object of the present invention is to provide a method and device for optimizing the design of main protection for an odd-number multi-branch wave winding generator in which a flexible optical TA and an electromagnetic TA are combined.

[0040] On the basis of comprehensive simulation and calculation of internal faults of generator by using "multi-loop analysis method", based on the branch grouping mode (3-1-3 or 4-1-4 or 5-1-5) of the existing odd-numbered multi-branch wave winding generator (a=7 / 9 / 11) and the arrangement of electromagnetic branch group TA and the type of inoperable fault, a flexible optical TA is wound on the "-1-" branch in a targeted manner, and incomplete longitudinal differential protection and corresponding complete longitudinal differential protection of the flexible optical TA connected to the neutral point side are added. Under the premise of not changing the branch grouping on the neutral point side of the generator, the copper ring lead-out mode and the arrangement of electromagnetic branch group TA, the protection dead zone for small-turn inter-turn / inter-phase short circuit is eliminated through the flexible winding of flexible optical TA and the optimized design of main protection.

[0041] The main steps are as follows:

[0042] Step 1: By analyzing the generator stator winding connection diagram provided by the motor manufacturer, according to the generator fault type analysis block diagram described in the large generator stator winding internal fault main protection configuration method (patent number: ZL200410009219.4) (see Figure 1 ), any two wire rods crossing in the slot or at the end are considered to have the possibility of same slot fault or end crossing fault, and the enumeration method is used to count the number of faults and their distribution characteristics of the same branch turn-to-turn short circuit, same phase but different branch turn-to-turn short circuit and phase-to-phase short circuit that may actually occur in the generator;

[0043] Step 2: Use the "multi-loop analysis method" to analyze and calculate the internal faults that may actually occur in the generator listed in step 1 (see Figure 2 ), obtain the magnitude and phase of each branch current under each fault (including the magnitude of the neutral point connection current), and then calculate the sensitivity coefficients of various commonly used main protection schemes to the internal faults listed in step 1, and determine the number and type of faults that various main protection schemes can respond to;

[0044] Step 3: Based on the advantages of various main protection schemes that have been understood in step 2, according to the design principle of "complementary advantages and comprehensive utilization", the main protection quantitative design flow chart of large and medium-sized generators is used (see Figure 3 ), recommend the generator main protection configuration scheme, strive to minimize the protection action dead zone, and require the least electromagnetic TA;

[0045] The quantitative design process includes initialization conditions, calling the generator fault type analysis subroutine, counting the number and type of internal faults actually occurring in the generator, calling the generator internal fault simulation calculation subroutine based on the multi-loop analysis method, calculating the performance indicators of various main protection schemes, and determining the lead-out method on the neutral point side of the generator from the type of transverse differential protection. If the performance of the zero-sequence current type transverse differential protection is better than that of the split-phase transverse differential protection, the zero-sequence current type transverse differential protection is selected, and the neutral point of the generator is led out in a corresponding manner. Otherwise, the split-phase transverse differential protection is selected, and only one neutral point is led out. The longitudinal differential protection is added to form a preliminary pattern of "one horizontal and one vertical", and the number and position of the branch TA are determined to determine whether the preliminary pattern meets the design requirements. If the design requirements are met, it is the final main protection configuration plan for power generation. If the design requirements are not met, the trade-offs and composition methods of the transverse differential and longitudinal differential protections are considered on the basis of quantitative analysis until the design indicators are met.

[0046]

[0047] Where N represents the type of main protection scheme, F Ai It is represented by the number of faults that a certain main protection scheme cannot operate, n is represented by the number of internal faults actually occurring in the generator, ε 1 Expressed as a design target, i.e., the size of the protection dead zone (in percentage).

[0048] Step 4: Retain the copper ring lead-out mode (3-1-3 or 4-1-4 or 5-1-5) and the branch group electromagnetic TA on the neutral point side of the odd-number multi-branch (a=7 / 9 / 11) wave winding generator. According to the quantitative design results of the generator main protection in step 3, a flexible optical TA is wound on the "-1-" branch in a targeted manner. The corresponding main protection scheme is added by combining the flexible optical TA and the electromagnetic TA to eliminate the protection dead zone for small-turn inter-turn / inter-phase short circuits. Under the premise of meeting the requirements of the quantitative design of the main protection in step 3, the corresponding main protection configuration scheme can further reduce the protection dead zone and improve the analysis and judgment of the generator in response to eccentric vibration accidents (see Figure 4 and Figure 5 ).

[0049] Example 2

[0050] The second embodiment of the present invention is different from the previous embodiment in that:

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] Example 3

[0056] The third embodiment of the present invention provides an optimization design system for the main protection of an odd-number multi-branch wave winding generator, which is characterized by comprising a fault enumeration analysis module, a loop analysis and calculation module, a main protection design module, and a protection scheme optimization module;

[0057] The fault enumeration analysis module uses the enumeration method to count the actual internal faults of the generator;

[0058] The loop analysis and calculation module uses the multi-loop analysis method to analyze and calculate the internal faults that occur;

[0059] The main protection design module recommends the configuration scheme of the main protection of the generator through the quantitative design process of the main protection of the generator;

[0060] The protection scheme optimization module retains the established copper ring lead-out method and branch group electromagnetic TA on the neutral point side of the odd-numbered multi-branch wave winding generator. According to the quantitative design results of the generator main protection, a flexible optical TA is wound on the branch. The main protection scheme is added through the combination of flexible optical TA and electromagnetic TA. While optimizing the main protection configuration scheme to reduce the protection dead zone, the analysis and judgment of the generator in response to eccentric vibration accidents is improved.

[0061] 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.

[0062] Example 4, reference Figure 6-Figure 8 , which is the fourth embodiment of the present invention.

[0063] The following takes the implementation of the Xiangjiaba ALSTOM generator (4×800MW) main protection optimization design (based on flexible optical TA) as an example to introduce how to achieve the optimization design of the main protection of the odd-numbered multi-branch wave winding generator based on a comprehensive internal short-circuit analysis and calculation.

[0064] The Xiangjiaba ALSTOM generator uses an integer slot (q = 3) "half-wave winding" (stator winding pitch is y 1 =10 / y 2 =8), 84 poles, 756 stator slots, 7 branches per phase, 36 coils per branch. By analyzing the stator winding expansion diagram of the generator provided by Tianjin Alstom Hydropower Equipment Co., Ltd., according to Figure 1 The generator fault type analysis block diagram is shown in Figure 1, and the actual internal short circuits that may occur are shown in Tables 1 and 2.

[0065] Table 1. 756 same-slot faults of ALSTOM generators in Xiangjiaba.

[0066]

[0067] Table 2. 12096 end cross faults of the Xiangjiaba ALSTOM generator.

[0068]

[0069]

[0070] The quantitative and optimal design method of generator main protection based on the "multi-loop analysis method" has been promoted and applied in the hydropower field. The internal fault analysis of stator windings and the quantitative design of main protection schemes have been carried out for generator sets of more than 170 large and medium-sized hydropower stations and pumped storage power stations at home and abroad. The existing design experience is summarized, and the existing main protection configuration schemes of odd-number multi-branch wave winding generators (such as Figure 6 The defects of the generator are as shown in the figure: there is a dead zone for phase-to-phase short-circuit protection with small turns on the neutral point side and it occurs between branches without electromagnetic TA installed; the lack of complete longitudinal differential protection makes it difficult to analyze and judge the eccentric vibration of the generator through the difference with the transverse differential protection action behavior.

[0071] Figure 6 The fault indicated by the dashed arrow in the middle is that the upper side of the 36th coil of the 4th branch of phase a and the lower side of the 33rd coil of the 4th branch of phase b are short-circuited at the intersection of the ends when the Xiangjiaba ALSTOM generator is in grid-connected no-load operation mode. The short-circuit points of the two short-circuited branches are close to the neutral point side. The magnitude (effective value, unit is A) and phase of the fundamental current of each branch (including the short-circuited additional branch) are as follows:

[0072]

[0073] Since the short-circuit points of the two short-circuit branches are close to the neutral point, a 4 、b 4 The number of short-circuit turns in the branches is small and almost the same, resulting in little change in the magnitude of the current on the neutral point side of the non-fault branch after the fault occurs, and the corresponding main protection scheme (such as Figure 6 The incomplete split phase differential protection and incomplete longitudinal differential protection shown in the figure both abandon the fault branch) because the operating current is too small and the sensitivity coefficient of the corresponding main protection scheme is not high. Taking the fault phase a as an example, Figure 6 The sensitivity coefficients of the incomplete phase-split transverse differential protection and the two sets of incomplete longitudinal differential protection shown are only 1.246, 0.570, and 0.676, respectively.

[0074] Based on the same concept, the short-circuit current and The size of the two branches is not much different, and the direction is almost opposite. 4 For b 4 ) occurs, a large short-circuit current does not flow through the neutral point connection (such as Figure 6 The red dotted line shows the sensitivity of the zero-sequence current type transverse difference. Figure 6 The sensitivity coefficients of the zero-sequence current type differential protection of TA01 and TA02 are only 1.367 and 1.151 respectively.

[0075] Since the machine-end phase current Neutral point side branch current The size and phase difference are large, which makes the incomplete longitudinal differential protection connected to the fourth branch on the neutral point side sensitive, and the corresponding sensitivity coefficient is 8.036.

[0076] Retaining full longitudinal differential protection in the generator main protection configuration scheme can not only respond to all phase-to-phase short-circuit faults, but also help analyze accidents caused by rotor eccentric vibration.

[0077] from Figure 7 (b) It can be seen that the complete longitudinal differential protection compares the imbalance of the phase current between the machine end and the neutral point side. In theory, it does not respond to the branch unbalanced current (both the transverse differential and incomplete longitudinal differential protections respond). Therefore, for generators with concentrated windings (stacked windings or "half-wave windings"), retaining a set of complete longitudinal differential protection in the main protection configuration scheme is helpful for analyzing accidents caused by rotor eccentric vibration (while monitoring the swing and air gap concentricity of the upper guide bearing, etc.) - that is, if the transverse differential or incomplete longitudinal differential protection in the generator main protection configuration scheme is activated or alarmed, but the complete longitudinal differential protection is not activated and the swing and air gap concentricity of the upper guide bearing exceed the standard, it is judged as rotor eccentric vibration, avoiding a series of misoperations such as pulling out the rotor.

[0078] This is the case in Pengshui (5×350MW / lap winding / 5 branches per phase, such as Figure 7 (a) The power station has been confirmed - during the first zero-start voltage rise test of Pengshui #2 generator, the incomplete phase split differential (reflecting the imbalance of the 12-45 branch current) actuated to cut off the machine (the unbalanced current in the differential circuit had reached 0.23Ign, and upon inspection, it was found that the inner circle of the stator was not round / the rotor was seriously eccentric), and the incomplete longitudinal differential protection also sounded an alarm, but its complete longitudinal differential protection did not act.

[0079] In the past ten years, flexible optical TA based on Faraday magneto-optical effect has been gradually applied in the field of hydropower and has accumulated certain engineering experience. It has not only solved the problems of saturation and poor low-frequency transmission characteristics of traditional electromagnetic TA, but also made use of its advantages of flexible winding and high measurement accuracy to "target" the flexible optical TA on the branch where electromagnetic TA is not installed. Through the combination of flexible optical TA and electromagnetic TA, the corresponding main protection scheme is added to eliminate the protection dead zone for small-turn inter-turn / phase-to-phase short circuit.

[0080] As described above, by winding a flexible optical CT on the 4th branch of each phase and adding corresponding incomplete longitudinal differential protection, the small-turn inter-turn short circuit between the same branches and the small-turn inter-phase short circuit on the neutral point side between the three-phase 4th branches can be eliminated. In addition, the phase current on the neutral point side of the generator can be obtained and complete longitudinal differential protection can be added by adding an optical TA on the 4th branch of each phase and the existing electromagnetic branch group TA, which is helpful for analyzing and judging the eccentric vibration of the generator rotor.

[0081] Table 3. Operation of the existing and optimized main protection configuration schemes for the same-slot and end faults of the Xiangjiaba ALSTOM generator.

[0082]

[0083] Table 4. Number and types of failures of the main protection configuration schemes that cannot be operated in the existing and optimized schemes when the main protection configuration schemes of the Xiangjiaba ALSTOM generator end are faulty.

[0084]

[0085] The proposed optimization design method for the main protection of the Xiangjiaba ALSTOM generator based on the combined arrangement of flexible optical TA and electromagnetic TA provides a new idea for the optimization design of the main protection of the odd-numbered multi-branch wave winding generator (a=7 / 9 / 11), that is, without increasing the difficulty of generator branch grouping (3-1-3 / 4-1-4 / 5-1-5), copper ring lead-out method and electromagnetic branch TA arrangement, the flexible optical TA is wound on the "-1-" branch in a targeted manner, and the corresponding main protection scheme is added to eliminate the protection dead zone for small-turn inter-turn / phase-to-phase short circuits, and improve the analysis and judgment of the generator in response to eccentric vibration accidents, achieving a "win-win" situation for the primary electrical profession (generator) and the secondary electrical profession (relay protection).

Claims

1. An optimization design method for main protection of an odd-number multi-branch wave winding generator, characterized in that: include, The enumeration method is used to count the actual internal faults of the generator; Use multi-loop analysis method to analyze and calculate the internal faults that occur; Recommend the generator main protection configuration scheme through the quantitative design process of generator main protection; The established copper ring lead-out method and branch group electromagnetic TA on the neutral point side of the odd-numbered multi-branch wave winding generator are retained. According to the quantitative design results of the generator main protection, a flexible optical TA is wound on a specific branch. The main protection scheme is added through the combined arrangement of a flexible optical TA and an electromagnetic TA. While optimizing the main protection configuration scheme to reduce the protection dead zone, the analysis and judgment of the generator in response to eccentric vibration accidents is improved.

2. The method for optimizing the design of main protection for an odd-number multi-branch wave winding generator according to claim 1, characterized in that: The internal faults include the number and distribution characteristics of short circuits between turns of the same branch, short circuits between turns of the same phase but different branches, and short circuits between phases.

3. The method for optimizing the design of main protection for an odd-number multi-branch wave winding generator according to claim 2, characterized in that: The analysis and calculation include inputting original data items, calculating the inductance coefficient of each stator coil generated by the air gap magnetic field, calculating the inductance coefficient of each stator coil generated by the end leakage magnetic field, calculating the resistance of each stator branch, calculating the self-inductance of the excitation circuit, calculating the inductance coefficient of the excitation circuit and each stator branch, calculating the inductance coefficient of the excitation circuit and each damping circuit, calculating the inductance coefficient of each damping circuit, calculating the inductance coefficient of each damping circuit and each stator branch, forming a state equation according to the fault state, solving it, and outputting the final result.

4. The method for optimizing the design of main protection for an odd-number multi-branch wave winding generator according to claim 3, characterized in that: The quantitative design process includes initialization conditions, calling the generator fault type analysis subroutine, counting the number and type of internal faults actually occurring in the generator, calling the generator internal fault simulation calculation subroutine based on the multi-loop analysis method, calculating the performance indicators of various main protection schemes, and determining the lead-out method on the neutral point side of the generator from the type of transverse differential protection. If the performance of the zero-sequence current type transverse differential protection is better than that of the split-phase transverse differential protection, the zero-sequence current type transverse differential protection is selected, and the neutral point of the generator is led out in a corresponding manner. Otherwise, the split-phase transverse differential protection is selected, and only one neutral point is led out. The longitudinal differential protection is added to form a preliminary pattern of "one horizontal and one vertical", and the number and position of the branch TA are determined to determine whether the preliminary pattern meets the design requirements. If the design requirements are met, it is the final main protection configuration scheme for power generation. If the design requirements are not met, the selection and composition methods of other transverse differential and longitudinal differential protections are considered on the basis of quantitative analysis until the design indicators are met.

5. The method for optimizing the design of main protection for an odd-number multi-branch wave winding generator according to claim 4, characterized in that: The analysis and judgment include a quantitative design scheme for the main protection of a multi-branch wave winding generator, and whether the protection dead zone of the existing generator main protection configuration scheme is a small-turn inter-turn or phase-to-phase short circuit on a branch or between branches without an electromagnetic TA installed. If not installed, a flexible optical TA is wound on the branch without an electromagnetic TA, and a corresponding main protection scheme is added to eliminate the protection dead zone for small-turn inter-turn or phase-to-phase short circuit. If installed, the final main protection configuration scheme of the generator has the smallest dead zone and is helpful for the analysis and judgment of the rotor eccentric vibration.

6. The method for optimizing the design of main protection for an odd-number multi-branch wave winding generator according to claim 4, characterized in that: The main protection scheme includes a set of incomplete phase-splitting transverse differential protection, a set of incomplete longitudinal differential protection and a set of complete longitudinal differential protection.

7. The method for optimizing the design of main protection for an odd-number multi-branch wave winding generator according to claim 5, characterized in that: The design index is expressed as: Where N represents the type of main protection scheme, F Ai It is represented by the number of faults for which a main protection scheme cannot be operated, n is represented by the number of internal faults actually occurring in the generator, and ε1 is represented by the design target.

8. A system based on the method for optimizing the design of main protection for an odd-numbered multi-branch wave winding generator according to any one of claims 1 to 7, characterized in that: Including fault enumeration analysis module, circuit analysis and calculation module, main protection design module, protection scheme optimization module; The fault enumeration analysis module uses the enumeration method to count the actual internal faults of the generator; The loop analysis and calculation module uses the multi-loop analysis method to analyze and calculate the internal faults that occur; The main protection design module recommends the configuration scheme of the main protection of the generator through the quantitative design process of the main protection of the generator; The protection scheme optimization module retains the established copper ring lead-out method and branch group electromagnetic TA on the neutral point side of the odd-numbered multi-branch wave winding generator. According to the quantitative design results of the generator main protection, a flexible optical TA is wound on a specific branch. The main protection scheme is added through the combined arrangement of flexible optical TA and electromagnetic TA. While optimizing the main protection configuration scheme to reduce the protection dead zone, the analysis and judgment of the generator in response to eccentric vibration accidents is improved.

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.

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