Generator tripping control optimization method based on direct-current power compensation and related device

Abstract

The invention discloses a generator tripping control optimization method based on direct-current power compensation and a related device, and the method comprises the steps: aiming at a multi-loop direct-current power transmission system comprising n direct-current power transmission lines with commutation failure and m direct-current power transmission lines without commutation failure, determining actual excess total energy accumulated in the commutation failure period, J lines for direct current compensation, actual compensation total energy and generator tripping offset energy; performing energy compensation on the J lines, and performing generator tripping operation on the n fault lines; and then acquiring system recovery operation data and judging whether a preset recovery condition is met or not, if so, determining the revocation priority and descending order of the J compensation lines, and revoking the J lines according to the order. Therefore, through cooperative execution of direct-current power compensation and generator tripping operation, accurate judgment of a recovery state and ordered revocation of a compensation line, safe and stable recovery of the multi-loop direct-current power transmission system after commutation failure is realized, and the stability of the system is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power systems, and particularly relates to a generator tripping control optimization method based on DC power compensation and related devices. BACKGROUND

[0002] A multi-loop DC power transmission system converts AC power into DC power through a sending-end converter station, transmits the DC power to a receiving-end converter station through a DC transmission line, and then converts the DC power into AC power to be distributed to users. However, the system has a problem of strong DC and weak AC power grid, which easily causes simultaneous commutation failure of multiple DC transmission lines when a single DC transmission line fails, and causes the power originally to be transmitted to the receiving end to be stranded in the sending-end AC grid, resulting in a sudden increase in the sending-end frequency and a sudden decrease in the receiving-end frequency, and further triggering a power angle instability and other cascading failures, which seriously threatens the safety of the power grid.

[0003] The prior art usually adopts a combination strategy of DC power compensation and generator tripping, that is, the short-time overload capacity of the non-fault DC line is used to increase the power to compensate for the excess energy at the sending end, and then part of the generator set is tripped to offset the remaining excess energy to balance the system power. However, the prior art has a single screening basis when selecting the target DC line for compensation, and only takes the condition that the DC compensation energy is equal to the excess energy as the only condition for system recovery, which leads to poor stability of the system.

[0004] Therefore, there is an urgent need for a generator tripping control optimization method to ensure the safe and stable operation and efficient recovery of the multi-loop DC power transmission system after a fault. SUMMARY

[0005] The embodiments of the present application provide a generator tripping control optimization method based on DC power compensation and related devices, which realizes safe and stable recovery of the multi-loop DC power transmission system after commutation failure through the cooperative execution of DC power compensation and generator tripping, accurate determination of the recovery state, and orderly withdrawal of the compensation line, and improves the stability of the system.

[0006] In a first aspect, the embodiments of the present application provide a generator tripping control optimization method based on DC power compensation, which comprises: obtaining actual total excess energy accumulated during commutation failure of n DC transmission lines in a multi-loop DC power transmission system; the multi-loop DC power transmission system comprises the n DC transmission lines and m DC transmission lines that do not have commutation failure; m and n are positive integers; determining J DC transmission lines among the m DC transmission lines to which DC compensation is put in according to the actual total excess energy; determining the sum of compensation energy generated by the J DC transmission lines to obtain actual total compensation energy; J is a natural number less than or equal to m; determining generator tripping offset energy according to the actual total excess energy and the actual total compensation energy; performing energy compensation operation based on the J DC transmission lines according to the actual compensation total energy, and performing generator tripping operation on the n DC transmission lines according to the generator tripping offset energy; acquire recovery operation data of the multi-loop DC power transmission system, and determine whether the recovery operation data meets a preset recovery condition; If yes, determine J revocation priorities of the J DC transmission lines, and determine a revocation priority descending order according to the J revocation priorities; perform line revocation on the J DC transmission lines in the revocation priority descending order to complete recovery of the multi-loop DC power transmission system.

[0007] In a second aspect, the embodiments of the present application provide a generator tripping control optimization device based on DC power compensation, which comprises an excess energy calculation module, a compensation line determination module, a generator tripping offset energy calculation module, a DC compensation and generator tripping control module, a system recovery data acquisition module, a revocation priority determination module, and a line revocation module, wherein, The excess energy calculation module is configured to acquire actual excess total energy accumulated during commutation failure of n DC transmission lines in a multi-loop DC power transmission system; the multi-loop DC power transmission system comprises the n DC transmission lines and m DC transmission lines that do not have commutation failure; m and n are positive integers. The compensation line determination module is configured to determine J DC transmission lines that are put into DC compensation among the m DC transmission lines according to the actual excess total energy; determine a sum of compensation energies generated by the J DC transmission lines to obtain actual compensation total energy; J is a natural number less than or equal to m. The generator tripping offset energy calculation module is configured to determine generator tripping offset energy according to the actual excess total energy and the actual compensation total energy. The DC compensation and generator tripping control module is configured to perform energy compensation operation based on the J DC transmission lines according to the actual compensation total energy, and perform generator tripping operation on the n DC transmission lines according to the generator tripping offset energy. The system recovery data acquisition module is configured to acquire recovery operation data of the multi-loop DC power transmission system, and determine whether the recovery operation data meets a preset recovery condition. The revocation priority determination module is configured to determine J revocation priorities of the J DC transmission lines when the recovery operation data meets the preset recovery condition, and determine a revocation priority descending order according to the J revocation priorities. The line revocation module is configured to perform line revocation on the J DC transmission lines in the revocation priority descending order to complete recovery of the multi-loop DC power transmission system.

[0008] In a third aspect, the embodiments of the present application provide an electronic device, comprising: a processor, a memory, a communication interface, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the processor, and the program includes instructions for performing the steps in the first aspect of the embodiments of the present application.

[0009] In a fourth aspect, the embodiments of the present application provide a computer readable storage medium, wherein the computer readable storage medium stores a computer program for electronic data exchange, and the computer program causes a computer to perform some or all of the steps described in the first aspect of the embodiments of the present application.

[0010] In a fifth aspect, the embodiments of the present application provide a computer program product, wherein the computer program product includes a non-transitory computer readable storage medium storing a computer program, and the computer program is operable to cause a computer to perform some or all of the steps described in the first aspect of the embodiments of the present application. The computer program product can be a software installation package.

[0011] It can be seen that, by adopting the embodiments of the present application, the following beneficial effects are achieved: By implementing the embodiments of the present application, the actual total excess energy accumulated during commutation failure of n DC transmission lines in a multi-loop DC transmission system is obtained; the multi-loop DC transmission system includes the n DC transmission lines and m DC transmission lines that have not occurred commutation failure; J DC transmission lines among the m DC transmission lines that are put into DC compensation are determined according to the actual total excess energy; the sum of compensation energy generated by the J DC transmission lines is determined to obtain actual total compensation energy; machine trip offset energy is determined according to the actual total excess energy and the actual total compensation energy; energy compensation operation is performed on the J DC transmission lines based on the actual total compensation energy, and machine trip operation is performed on the n DC transmission lines according to the machine trip offset energy; recovery operation data of the multi-loop DC transmission system is obtained, and it is judged whether the recovery operation data meets a preset recovery condition; if yes, J priority revocation priorities of the J DC transmission lines are determined, and priority revocation descending order is determined according to the J priority revocation priorities; the J DC transmission lines are revoked in the priority revocation descending order to complete recovery of the multi-loop DC transmission system. It can be seen that, through the cooperative execution of DC power compensation and machine trip operation, the accurate determination of the recovery state and the orderly revocation of the compensation lines, the safe and smooth recovery of the multi-loop DC transmission system after commutation failure is realized, and the stability of the system is improved. BRIEF DESCRIPTION OF DRAWINGS

[0012] In order to make the technical scheme in the application or the background art clearer, the accompanying drawings needed to be used in the application or the background art will be described below.

[0013] Figure 1 is a flowchart of a machine trip control optimization method based on DC power compensation provided by the application embodiment; Figure 2 is a flowchart of determining a DC compensation line that can be put into provided by the application embodiment; Figure 3 is a flowchart of calculating compensation degree and tie line stability index provided by the application embodiment; Figure 4 is a flowchart of screening a DC compensation line that can be put into provided by the application embodiment; Figure 5 is a flowchart of obtaining recovery operation data provided by the application embodiment; Figure 6 is a flowchart of calculating a revocation priority provided by the application embodiment; Figure 7 is a structural diagram of a machine trip control optimization device based on DC power compensation provided by the application embodiment; Figure 8 is a structural diagram of an electronic device provided by the application embodiment. DETAILED DESCRIPTION

[0014] In order to make the technical scheme in the application or the background art clearer, the accompanying drawings needed to be used in the application or the background art will be described below.

[0015] The terms "first", "second", etc. in the specification and claims of the application and the above-mentioned drawings are used to distinguish different objects, and are not used to describe a specific order. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device including a series of steps or units is not limited to the listed steps or units, but can optionally include steps or units not listed, or can optionally include other steps or units inherent to the process, method, product or device.

[0016] Reference to an "embodiment" herein means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily mutually exclusive of one another. As will be apparent to those of ordinary skill in the art, embodiments described herein can be combined with other embodiments.

[0017] The following describes related content, concepts, meanings, technical problems, technical solutions, beneficial effects, etc. involved in embodiments of the application.

[0018] First, some terms involved in the application are explained: Commutation failure: Commutation failure refers to a temporary fault in which a commutator in a DC power transmission system cannot normally complete the commutation process due to reasons such as voltage drop on the AC side, harmonic interference, etc. This fault will cause a sudden drop in the transmission power of the DC power transmission line.

[0019] See Figure 1 , Figure 1 is a flowchart of a generator tripping control optimization method based on DC power compensation provided by an embodiment of the application. The method includes but is not limited to the following steps: S101, acquiring actual total excess energy accumulated during commutation failure of n DC power transmission lines in a multi-loop DC power transmission system; the multi-loop DC power transmission system includes the n DC power transmission lines and m DC power transmission lines that have not experienced commutation failure.

[0020] In an embodiment of the application, m and n are positive integers. For example, a multi-loop DC power transmission system has 10 DC power transmission lines, of which 4 DC power transmission lines experience commutation failure and 6 DC power transmission lines do not experience commutation failure.

[0021] In an embodiment of the application, the actual total excess energy refers to the total amount of electric energy that was originally to be transmitted to the receiving end but was stranded in the sending end AC network during commutation failure of the n DC power transmission lines in the multi-loop DC power transmission system.

[0022] In specific embodiments, for the n DC power transmission lines that experience commutation failure in the multi-loop DC power transmission system, the instantaneous power of each line during commutation failure, the initial power corresponding to the initial moment of commutation failure, and the moment when each line recovers to the initial power can be collected. Based on these parameters, the actual excess energy of each faulty line can be calculated.

[0023] The actual excess energy can be calculated by the following formula:

[0024] In the above formula, actual excess energy generated by the i-th DC transmission line indicating commutation failure; time indicating initial moment of commutation failure fault; time indicating the i-th DC transmission line commutation failure fault recovery to initial power; instantaneous power of the i-th DC transmission line between the initial moment of commutation failure fault and the time of recovery to initial power of commutation failure fault; initial power of the i-th DC transmission line.

[0025] It should be noted that the DC transmission line with commutation failure can be self-eliminated and naturally recovered to the initial power, that is, the converter can automatically recover to normal commutation function without manual or external control intervention, and the transmission power of the DC line will gradually rise to the initial power before the fault. Therefore, the actual excess energy retained by the DC transmission line during the commutation failure needs to be calculated. In subsequent DC compensation, the DC transmission line with commutation failure does not participate in DC compensation.

[0026] After obtaining the actual excess energy of each DC transmission line of the n DC transmission lines with commutation failure, the actual excess total energy accumulated by the multi-loop DC transmission system during the commutation failure can be obtained by adding.

[0027] It can be seen that by accurately calculating the actual excess total energy during the commutation failure, reliable data support can be provided for subsequent DC power compensation and generator tripping operation.

[0028] S102, determining J DC transmission lines from the m DC transmission lines for DC compensation according to the actual excess total energy; determining the sum of compensation energies generated by the J DC transmission lines to obtain an actual compensation total energy.

[0029] In the embodiments of the present application, J is a natural number less than or equal to m. Although the m lines without commutation failure all have compensation potential, there are differences in stability and compensation efficiency of different lines. If all the m lines are blindly put into compensation, the sending end frequency may drop due to the compensation energy far exceeding the actual excess total energy, and if too few lines are put into compensation, the generator tripping amount cannot be effectively reduced. Therefore, it is necessary to select J DC transmission lines from the m DC transmission lines for DC compensation.

[0030] In specific embodiments, J DC transmission lines with short-time power boosting capability and meeting system stability requirements are selected from the m DC transmission lines. The total energy obtained by adding the additional electric energy (i.e. the compensation energy of a single line) of each line by short-time boosting transmission power can basically be used to offset the actual excess total energy retained by the sending end AC network due to commutation failure.

[0031] Then, the sum of compensation energy generated by J DC transmission lines is determined, and the actual total compensation energy can be obtained. The actual total compensation energy can explicitly indicate the offset degree of DC compensation to the actual total surplus energy. If the actual total surplus energy cannot be completely offset, the actual total surplus energy can be completely offset by generator tripping operation, so that the target of mainly using DC compensation and secondarily using generator tripping can be achieved.

[0032] Please refer to Figure 2 , Figure 2 is a flowchart for determining DC compensation lines according to an embodiment of the present application. Optionally, the step of determining J DC transmission lines from the m DC transmission lines according to the actual total surplus energy comprises the following steps: A201, obtaining a surplus energy segmentation table and a maximum energy value of the surplus energy segmentation table; the surplus energy segmentation table is composed of multiple intervals according to the size of energy values; each interval corresponds to the number of lines that can be put into DC compensation; A202, determining the compensation degree of the m DC transmission lines and the first tie line stability index, to obtain m compensation degrees and m first tie line stability indexes; A203, if the actual total surplus energy is less than or equal to the maximum energy value, determining the target interval corresponding to the actual total surplus energy in the surplus energy segmentation table; A204, selecting the J DC transmission lines from the m DC transmission lines according to the number of lines that can be put into DC compensation corresponding to the target interval and the m compensation degrees; J is equal to the number of lines that can be put into DC compensation corresponding to the target interval; A205, if the actual total surplus energy is greater than the maximum energy value, determining the maximum number of lines that can be put into DC compensation corresponding to the maximum interval in the surplus energy segmentation table; A206, screening J DC transmission lines that can be put into DC compensation from the m DC transmission lines according to the actual total surplus energy, the m compensation degrees and the m first tie line stability indexes, to obtain the J DC transmission lines; J is greater than or equal to the maximum number of lines that can be put into DC compensation.

[0033] In the embodiment of the present application, the surplus energy segmentation table is pre-divided into multiple continuous intervals according to the loss of commutation failure energy value from small to large in combination with the line capacity, short-time overload capacity and historical fault data of the multi-circuit DC transmission system, and a standardized table of the number of lines that can be put into DC compensation and the amount of generator tripping after fault is configured for each interval. The surplus energy segmentation table is shown in Table 1: Table 1 Surplus energy segmentation table

[0034] In the above table, the energy value column of commutation failure loss defines the range of each interval; the DC column indicates the number of compensation lines adapted to each interval; the amount of generator tripping column corresponds to the actual total excess energy after the compensation lines are put into operation, and the actual total excess energy is compensated by generator tripping. The table needs to be stored in the system control database in advance to ensure that the interval division matches the actual compensation demand.

[0035] In the interval (0, W dmin ] corresponding to the DC compensation DC transmission line is 0, that is, the energy scale is extremely small, if the DC transmission line is put into compensation, on the one hand, the short-time overload compensation of the DC transmission line has an operation delay (such as millisecond-level response for power increase), and the excess energy may have caused a small frequency fluctuation before the compensation starts; on the other hand, the DC transmission line needs to occupy additional grid dispatching resources, and a small amount of loss will be generated due to the overload of the line, and the compensation cost (dispatching cost + loss cost) may be higher than the cost of a small amount of generator tripping. Therefore, the compensation mode of only generator tripping is selected, which not only simplifies the control process, but also quickly offsets the small excess energy at the lowest cost.

[0036] In the embodiments of the present application, the maximum energy value is the upper limit of the excess energy segmentation table, that is, the upper limit W dmins-1 of the interval (W dmax , W dmax ] in Table 1, which represents the maximum commutation failure loss energy that can be covered by the table, and if it exceeds this value, the maximum compensation configuration preset by the table needs to be broken through. The number of DC compensation lines that can be put into operation corresponding to the interval (W dmins-1 , W dmax ] is the maximum number of lines s, which is the maximum compensation line scale preset.

[0037] When the actual total excess energy is large, if the maximum compensation configuration preset by the table is broken through, more generator tripping is needed to compensate for the energy, which will increase the cost and the problem of grid stability, therefore, on the basis of the maximum number of lines, the number of target DC transmission lines can be increased according to the compensation degree of the DC transmission line that has not occurred commutation failure.

[0038] In the embodiments of the present application, the first tie line stability index is a quantitative index for evaluating the power transmission stability of the associated tie line when the single DC transmission line without fault participates in compensation, and the first tie line stability index needs to meet a preset threshold to avoid instability of the tie line caused by compensation.

[0039] In specific embodiments, the pre-stored excess energy segmentation table and the maximum energy value of the table can be called from the system control database.

[0040] Then, the compensation degree of the m DC transmission lines and the first interconnection line stability index are determined, and m compensation degrees and m first interconnection line stability indexes are obtained.

[0041] If the actual total excess energy is less than or equal to the maximum energy value, the actual total excess energy is determined to be in the target interval corresponding to the excess energy segmentation table, and J DC transmission lines are selected from the m DC transmission lines according to the number of lines that can be compensated by DC corresponding to the target interval. According to the number of lines that can be compensated by DC corresponding to the target interval and the m compensation degrees, J DC transmission lines can be selected from the m DC transmission lines, wherein J is equal to the number of lines that can be compensated by DC corresponding to the target interval.

[0042] Specifically, the m compensation degrees can be sorted, and the corresponding DC transmission lines with high compensation degrees are preferentially selected. Of course, at this time, the interconnection line stability index can not be considered, because the number of lines that can be compensated by DC corresponding to the target interval in the excess energy segmentation table has been verified by system simulation in advance, and the stability margin of the selected DC transmission lines can meet the basic safety requirements, without the need for additional screening by the stability index. And preferentially selecting the corresponding DC transmission lines with high compensation degrees can maximize the compensation efficiency under the premise of ensuring system stability, quickly offset the actual total excess energy, avoid the delay of compensation response caused by introducing the stability index for screening, and simplify the screening logic and reduce the real-time operation load.

[0043] If the actual total excess energy is greater than the maximum energy value, the maximum number of lines that can be compensated by DC corresponding to the maximum interval in the excess energy segmentation table is determined. According to the actual total excess energy, the m compensation degrees and the m first interconnection line stability indexes, J DC transmission lines that can be compensated by DC can be screened from the m DC transmission lines, and J DC transmission lines are obtained. Wherein J is greater than or equal to the maximum number of lines that can be compensated by DC to cover the excess energy.

[0044] Through the excess energy segmentation table, fast compensation line screening under the conventional energy scale can be realized, and repeated calculation can be avoided; when the actual total excess energy exceeds the coverage range of the excess energy segmentation table, by introducing the compensation degree and the stability index, the preset limit of the table is broken through, and the safety and efficiency of the newly added lines are ensured, while always giving priority to compensation to reduce the amount of machine cutting and avoid the loss of power generation caused by pure machine cutting, so as to improve the stability and economy of the system.

[0045] Please refer to Figure 3 , Figure 3 is a flowchart of a process for calculating a compensation degree and an interconnection line stability index provided by an embodiment of the present application. Optionally, the above-mentioned step of determining the compensation degree of the m DC transmission lines and the first interconnection line stability index to obtain m compensation degrees and m first interconnection line stability indexes specifically includes the following steps: B201, determining the line transient energy, the maximum line transient energy and the maximum line active power corresponding to the maximum line transient energy of the m DC transmission lines during the commutation failure according to the preset line transient energy calculation formula, obtaining m line transient energies, m maximum line transient energies and m maximum line active powers; B202, determining the m compensation degrees according to the m line transient energies; B203, determining the m first tie-line stability indexes according to the m maximum line transient energies and the m maximum line active powers.

[0046] In the embodiments of the present application, the preset line transient energy calculation formula is a mathematical expression pre-set for quantifying the transient energy state of the non-fault DC transmission line during the commutation failure. The line transient energy of the DC transmission line can be calculated through the preset line transient energy calculation formula. The preset line transient energy calculation formula can be as follows:

[0047] In the above formula, represents the line transient energy of the kth DC transmission line; represents the initial time of the commutation failure fault; represents the time when the kth DC transmission line recovers to the initial power after the commutation failure fault; represents the real-time active power of the kth DC transmission line; represents the instantaneous active power at the time of the commutation failure fault; represents the phase angle difference of the voltage at both ends of the kth DC transmission line; represents the phase angle difference change rate.

[0048] The maximum line transient energy refers to the maximum value of all the line transient energy values obtained by the preset line transient energy calculation formula during the commutation failure of the non-fault DC transmission line, i.e. between the initial time of the commutation failure fault and the time when the initial power is recovered, which reflects the maximum energy scale stored in the transient process of the line. The maximum line active power refers to the real-time active power corresponding to the maximum line transient energy when the non-fault DC transmission line reaches the maximum line transient energy.

[0049] In specific embodiments, the line transient energy of the m DC transmission lines during the commutation failure can be determined according to the preset line transient energy calculation formula, and the maximum line transient energy is obtained by screening out the maximum value of all the line transient energy values during the time period from the initial time of the commutation failure fault to the time when the initial power is recovered. The maximum line active power corresponding to the maximum line transient energy is determined, and then the m line transient energies, the m maximum line transient energies and the m maximum line active powers are obtained.​

[0050] The m compensation degrees are determined according to the m line transient state potential energies, wherein the compensation degree can be calculated by the following formula:

[0051] In the above formula, denotes the compensation degree of the jth DC transmission line; denotes the line transient state potential energy of the jth DC transmission line; denotes the line transient state potential energy of the kth DC transmission line in the m DC transmission lines.

[0052] The m first tie-line stability indexes are determined according to the m maximum line transient state potential energies and the m maximum line active powers, wherein the first tie-line stability index can be calculated by the following formula:

[0053] In the above formula, denotes the first tie-line stability index of the kth DC transmission line; denotes the maximum line active power of the kth DC transmission line; denotes the maximum line transient state potential energy of the kth DC transmission line; denotes the instantaneous active power when the commutation failure fault occurs.

[0054] It can be seen that by accurately calculating the line transient state potential energy, the compensation degree and the first tie-line stability index, quantitative support is provided for the compensation potential and stability capacity of the non-fault line, the blindness of the compensation line selection is effectively avoided, the J compensation lines put into operation are ensured to be efficient and safe, and the reliability of the multi-loop DC transmission system fault compensation is improved.

[0055] Please refer to Figure 4 , Figure 4 is a flowchart provided by an embodiment of the present application for screening DC compensation lines that can be put into operation. Optionally, the above-mentioned step of screening J DC transmission lines that can be put into operation from the m DC transmission lines according to the actual total excess energy, the m compensation degrees and the m first tie-line stability indexes to obtain the J DC transmission lines specifically comprises the following steps: C201, screening h DC transmission lines from the m DC transmission lines according to the m first tie-line stability indexes; the first tie-line stability index corresponding to each DC transmission line in the h DC transmission lines is greater than or equal to a preset first tie-line stability index threshold; h is a positive integer less than or equal to m; C202. Select J DC transmission lines from the h DC transmission lines; the absolute value of the difference between the sum of the compensation energy of the J DC transmission lines and the actual total excess energy is the smallest, and the sum of the compensation degree corresponding to the J DC transmission lines is the largest.

[0056] In this embodiment, the preset first tie line stability index threshold is a critical value set in advance based on the tie line transmission capacity, line withstand capability, and system stability margin of the multi-circuit DC transmission system. It is used to determine whether a non-faulty DC transmission line is qualified to participate in DC compensation. This threshold is usually not less than 0.005. Only when the first tie line stability index of the line is greater than or equal to this threshold can it be included in the candidate compensation line range, so as to avoid the tie line power oscillation or phase angle instability caused by the compensation operation.

[0057] In a specific embodiment, based on m first tie line stability indices, h DC transmission lines corresponding to first tie line stability indices greater than or equal to a preset first tie line stability index threshold can be selected from the m DC transmission lines, where h is a positive integer less than or equal to m.

[0058] Next, J DC transmission lines were selected from h DC transmission lines. Among them, the J selected DC transmission lines had the smallest absolute difference between the sum of their compensation energy and the actual total excess energy, and the J DC transmission lines had the largest sum of their corresponding compensation degrees. The absolute value of the difference between the sum of the compensation energy of the J DC transmission lines and the actual total excess energy is an indicator that quantifies the degree of matching between the compensation energy and the actual total excess energy. The smaller the absolute value of the difference, the closer the compensation energy is to the actual total excess energy, which can effectively reduce the risk of increased generator tripping due to insufficient compensation or frequency drop caused by overcompensation.

[0059] Specifically, from the h candidate lines, all possible combinations containing J lines can be generated. For each combination, the sum of compensation degrees F can be calculated using the following formula, and the candidate combination with the largest F value can be selected to ensure optimal compensation efficiency of the combination:

[0060] In the above formula, This represents the sum of compensation degrees; This represents the compensation degree of the j-th DC transmission line.

[0061] On the other hand, the sum of compensation energy for each candidate combination is calculated, and then the absolute value of the difference between the sum of compensation energy and the actual total excess energy is solved, and the combination with the smallest absolute value of the difference is selected.

[0062] Ultimately, the combination that simultaneously satisfies the maximum sum of compensation degrees and the minimum absolute value of energy difference was determined as J DC transmission lines that can be put into DC compensation.

[0063] The first tie line stability index directly determines the system safety when the line participates in compensation. The preset first tie line stability index threshold is used for screening, which can avoid the risk caused by unstable lines. The sum of compensation degrees is used as the core screening condition. The line combination with higher compensation degree can provide stronger compensation capacity when the same number of lines is put into operation, which can maximize the reduction of the dependence on machine trip operation. In combination with the condition that the absolute value of energy difference is minimum, the deviation of compensation energy and actual total excess energy is avoided to be too large, and the compensation effect and system demand are accurately matched.

[0064] It can be seen that, by screening safe candidate lines according to the stability threshold first, and then screening target lines according to compensation efficiency and energy matching degree, the J compensation lines selected can not only have safe operation conditions, but also can efficiently and accurately offset the actual total excess energy, effectively reduce the amount of machine trip after failure, avoid system risks caused by insufficient or excessive compensation, and significantly improve the safety, accuracy and economy of fault compensation of the multi-loop direct current transmission system.

[0065] S103, determining a machine trip offset energy according to the actual total excess energy and the actual total compensation energy.

[0066] In the embodiment of the application, the machine trip offset energy refers to the energy offset by cutting off the generator set at the sending end to balance the power supply and demand of the sending end AC network after the multi-loop direct current transmission system fails to commutate.

[0067] In specific embodiments, the machine trip offset energy can be calculated by the following formula:

[0068] In the above formula, represents the actual excess energy generated by the nth direct current transmission line that fails to commutate; represents the actual compensation energy compensated by the mth direct current transmission line that does not fail to commutate; represents the machine trip offset energy. represents the actual total excess energy; represents the actual total compensation energy.

[0069] S104, performing an energy compensation operation based on the J direct current transmission lines according to the actual total compensation energy, and performing a machine trip operation on the n direct current transmission lines according to the machine trip offset energy.

[0070] In the embodiments of the present application, the energy compensation operation refers to the operation of issuing power adjustment instructions by the control system to the J DC transmission lines that have not failed to commutate to increase the DC transmission power within the short-time overload capacity range, so as to offset the actual excess total energy of the sending end AC network retained after the commutation failure of the multi-circuit DC transmission system in the form of additional power transmission. The operation needs to determine the power increase amplitude and duration of each line based on the actual compensation total energy to ensure that the total compensation energy accurately matches the demand.

[0071] In the embodiments of the present application, the generator tripping operation refers to the operation of selecting appropriate generator units in the sending end AC network according to the generator tripping offset energy, for example, the units with fast adjustment response and low tripping cost can be preferentially selected, and the units with corresponding power scale are tripped by control instructions to directly reduce the total power generation of the sending end to balance the difference between the actual excess total energy and the actual compensation total energy, which is also used to ensure system power balance.

[0072] In specific embodiments, based on the J DC transmission lines, the actual compensation total energy can be reasonably allocated to each line according to the actual compensation total energy, the compensation degree of each line and the upper limit of short-time overload, and the power increase amount and compensation duration of each line are determined; then the control system issues power adjustment instructions to the converters of the J lines to control the lines to gradually increase the transmission power to the target value, and maintain the power level until the compensation duration ends to complete the energy compensation.

[0073] At the same time, for the generator tripping operation, the total power of the generator units to be tripped is calculated according to the generator tripping offset energy, the units to be tripped are selected in combination with the operating state of the sending end units, and the tripping instructions are issued to trip the units with corresponding power, and the generator tripping operation and the energy compensation operation are started synchronously to ensure real-time balance of power supply and demand of the sending end AC network.

[0074] It can be seen that through the cooperative execution of the energy compensation and the generator tripping operation, the compensation potential of the non-fault lines can be maximized to reduce the amount of tripped generators, and the power balance can be ensured through the tripped generators, which effectively improves the stability and economy of the multi-circuit DC transmission system after failure, and reduces the loss of power generation caused by excessive tripping.

[0075] S105, acquiring recovery operation data of the multi-circuit DC transmission system, and judging whether the recovery operation data meets a preset recovery condition.

[0076] In the embodiments of the present application, the preset recovery condition refers to a set of judgment thresholds that are set in advance in combination with the system rated operation standard, stability margin and safety demand, and is used to define whether the system has reached a stable level that can execute the compensation line withdrawal operation.

[0077] In specific embodiments, recovery operation data of the multi-circuit DC power transmission system can be acquired, and it is determined whether the recovery operation data meets preset recovery conditions. If the recovery operation data meets the preset recovery conditions, it is determined that the system has recovered to a stable state, and the subsequent compensation line revocation link can be entered. If the recovery operation data does not meet the preset recovery conditions, the recovery operation data is continuously acquired and repeated comparison is performed until the recovery operation data meets the preset recovery conditions.

[0078] After energy compensation and generator tripping operation, the system can still be in a transient adjustment stage, and parameters such as sending end frequency and tie-line power can fluctuate. If the compensation line is blindly revoked at this time, the system power imbalance can be easily caused again, and frequency abnormalities or tie-line instability can be caused. Therefore, by acquiring recovery operation data and verifying whether the preset recovery conditions are met, the actual stable state of the system can be accurately controlled, and it is ensured that the recovery operation is started only when the system has sufficient stability margin, thereby avoiding the risk of secondary faults.

[0079] Please refer to Figure 5 , Figure 5 is a flowchart for acquiring recovery operation data provided by the embodiments of the present application. Optionally, the recovery operation data includes: sliding window average frequency, frequency standard deviation, frequency change rate, J second tie-line stability indicators. The above steps of acquiring the recovery operation data of the multi-circuit DC power transmission system specifically include the following steps: A501, acquiring real-time operation parameters of the multi-circuit DC power transmission system in a preset recovery time period; the real-time operation parameters include: time length of a sliding window, instantaneous frequency set, rated frequency; the instantaneous frequency set is the instantaneous frequency of each time in the sliding window in the preset recovery time period; A502, determining the sliding window average frequency and the frequency change rate according to the time length of the sliding window and the instantaneous frequency set; A503, determining the frequency standard deviation according to the instantaneous frequency set and the rated frequency; the frequency standard deviation is the dispersion degree of the deviation value of each instantaneous frequency in the instantaneous frequency set from the rated frequency; A504, determining the second tie-line stability indicators of the J DC power transmission lines to obtain the J second tie-line stability indicators.

[0080] In the embodiments of the present application, the recovery operation data includes: sliding window average frequency, frequency standard deviation, frequency change rate, J second tie-line stability indicators.

[0081] In the embodiments of the present application, the preset recovery time period is a continuous time interval set in advance in combination with the transient response characteristics of the multi-circuit DC power transmission system, the energy compensation duration and the system stability estimation time after the generator tripping operation. The start and end time of the preset recovery time period needs to cover the key process of the transition of the system from the fault adjustment phase to the stable operation phase, so as to ensure that the recovery trend of the system operation parameters can be completely captured for the subsequent recovery state evaluation.

[0082] The second tie-line stability index is a tie-line stability quantitative parameter recalculated for the J DC power transmission lines put into DC compensation in the system recovery phase. The calculation logic is consistent with that of the first tie-line stability index, but the parameter values are based on the actual operation data of the lines in the recovery phase, such as the maximum line active power and the maximum line transient potential in the recovery process, which are used to dynamically evaluate the stability margin of the lines and the associated tie-line in the recovery process, so as to ensure that the compensation lines still have safe operation conditions in the recovery phase.

[0083] In specific embodiments, real-time operation parameters of the multi-circuit DC power transmission system in the preset recovery time period are obtained, wherein the real-time operation parameters include: the time length of the sliding window, the instantaneous frequency set, and the rated frequency. The instantaneous frequency set is the instantaneous frequency of the sliding window at each time in the preset recovery time period, and the rated frequency is usually 50 Hz.

[0084] The sliding window average frequency and the frequency change rate can be determined according to the time length of the sliding window and the instantaneous frequency set, wherein the sliding window average frequency can be calculated by the following formula:

[0085] In the above formula, represents the sliding window average frequency; represents the time length of the sliding window; represents the end time of the preset recovery time period; represents the instantaneous frequency at the time in the preset recovery time period.

[0086] The frequency change rate can be calculated by the following formula:

[0087] In the above formula, represents the frequency change rate, which is the maximum value of the absolute value of the derivative in the preset recovery time period; represents the instantaneous frequency at the time in the preset recovery time period.

[0088] ​​The frequency standard deviation can be determined according to the instantaneous frequency set and the rated frequency, wherein the frequency standard deviation is a dispersion degree of deviation values of each instantaneous frequency in the instantaneous frequency set from the rated frequency, that is, the dispersion degree of the deviation values is obtained by calculating a sum of squares of the deviation values, an average value and square root.

[0089] Then, the second tie-line stability indexes of the J DC transmission lines are calculated, and J second tie-line stability indexes are obtained, wherein the second tie-line stability index of the kth DC transmission line can be calculated by the following formula:

[0090] In the above formula, denotes the second tie-line stability index of the kth DC transmission line; denotes the maximum line active power of the kth DC transmission line; denotes the maximum line transient potential energy of the kth DC transmission line.

[0091] It can be seen that the key indicators in the recovery operation data are accurately collected and calculated, the recovery state of the multi-circuit DC transmission system can be comprehensively and objectively evaluated, the recovery state misjudgment caused by data loss or single indicator can be effectively avoided, and the smooth transition of the system from the fault state to the stable operation state is ensured.

[0092] Optionally, the preset recovery condition includes that an absolute value of a difference between the sliding window average frequency and the rated frequency is less than or equal to a preset average frequency threshold, the frequency standard deviation is less than or equal to a preset frequency standard deviation threshold, the frequency change rate is less than or equal to a preset upper limit of the frequency change rate, and the J second tie-line stability indexes are all greater than or equal to a preset second tie-line stability index threshold.

[0093] In the embodiments of the application, the preset average frequency threshold is a critical value that is set in advance in combination with a frequency stability margin of the multi-circuit DC transmission system, a frequency tolerance range of the generator set and the power consumption equipment, and is used to determine whether the deviation of the sliding window average frequency from the rated frequency is in a safe interval, and is usually 0.1-0.2 Hz.

[0094] The preset frequency standard deviation threshold is a preset allowed upper limit for measuring the degree of system frequency fluctuation, and is a critical value that is set based on the transient regulation capacity of the system and the anti-interference requirement of the equipment, and if the frequency standard deviation exceeds the value, it indicates that the system frequency is still in a state of frequent and large amplitude oscillation and has not reached the basic condition for stable operation.

[0095] The preset upper limit of the frequency change rate is a safety threshold for limiting the frequency change rate, and can be 0.25 Hz / s, which is used to prevent the impact damage to the generator set speed, the transformer insulation performance and the like caused by the too fast rise or fall of the frequency, and to ensure the safe operation of the equipment.

[0096] The preset second tie-line stability index threshold is a critical value for determining whether the Jth compensation line is stable in the recovery phase. For example, the value can be 0.005, which is consistent with the first tie-line stability index threshold, to ensure that the compensation line can maintain the stable transmission state of the associated tie-line during the recovery process and avoid the instability of the tie-line caused by the recovery operation.

[0097] In specific embodiments, the preset recovery condition includes the following conditions:

[0098]

[0099]

[0100]

[0101] In the above formula, represents the sliding window average frequency; represents the rated frequency; represents the preset average frequency threshold; represents the frequency standard deviation; represents the preset frequency standard deviation threshold; represents the frequency change rate; represents the preset upper limit of the frequency change rate, which can be 0.25 Hz / s; represents the second tie-line stability index of the kth DC transmission line.

[0102] Specifically, the first term of the preset recovery condition uses the absolute value operation to eliminate the influence of the frequency deviation direction (higher or lower than the rated frequency), and only focuses on the deviation value, to ensure that the difference between the sliding window average frequency and the rated frequency is controlled within a safe range, and the overall system frequency is stable.

[0103] The second term of the preset recovery condition ensures that the fluctuation dispersion of the system frequency within the preset recovery time period does not exceed the allowed upper limit, and the frequency does not have large and frequent shocks, and the device operating environment is stable. The third term of the preset recovery condition ensures that the change rate of the system frequency does not exceed the safe upper limit of 0.25 Hz / s, to avoid the impact of sudden frequency rise and fall on the generator set and power transmission equipment. The fourth term of the preset recovery condition checks whether the J second tie-line stability indexes are all greater than or equal to the preset second tie-line stability index threshold one by one, to ensure that the associated tie-line of each compensation line has sufficient stability margin in the recovery phase and has no instability risk.

[0104] Only when the four conditions of the preset recovery condition are all met at the same time, it can be determined that the recovery operation data of the multi-circuit DC power transmission system meets the preset recovery condition; if any condition does not meet the requirement, it is determined that the system has not reached the recovery requirement, and needs to be continuously monitored and re-verified.

[0105] It can be seen that through the synchronous verification of the multi-dimensional preset recovery condition, the recovery stability of the multi-circuit DC power transmission system can be comprehensively and strictly determined.

[0106] S106, if yes, determine J revocation priorities of the J DC power transmission lines, and determine a revocation priority descending order according to the J revocation priorities.

[0107] In the embodiments of the present application, the revocation priority refers to a quantitative index for defining the sequence of revoking compensation operation of each line after the multi-circuit DC power transmission system meets the preset recovery condition, and the numerical value directly corresponds to the emergency degree of line revocation. The higher the priority, the earlier the revocation operation is performed, and the lower the priority, the later the revocation is performed.

[0108] The revocation priority descending order refers to an operation sequence formed by arranging the revocation priorities of the J DC power transmission lines in descending order of numerical value. The subsequent revocation compensation operation will be performed in this sequence to avoid system power imbalance or tie-line instability caused by chaotic revocation sequence.

[0109] In specific embodiments, if the recovery operation data meets the preset recovery condition, the key operation parameters of the J DC power transmission lines in the recovery phase are retrieved, and then the J revocation priorities of the J DC power transmission lines are calculated according to the key operation parameters. The J revocation priorities are compared in value, sorted in descending order, and the revocation priority descending order is determined. For example, the priority of line 1 is 9.2, the priority of line 2 is 7.5, and the priority of line 3 is 8.8. The descending order is line 1, line 3, and line 2.

[0110] Please refer to Figure 6 , Figure 6 is a flowchart of calculating the revocation priority provided by the embodiments of the present application. Optionally, the above step of determining the J revocation priorities of the J DC power transmission lines specifically includes the following steps: A601, determining a target compensation degree of a target DC power transmission line, and a first weight corresponding to the target compensation degree; the target DC power transmission line is any one of the J DC power transmission lines; A602, determining a target margin ratio of the operating power margin and the maximum power margin of the target DC power transmission line, and a second weight corresponding to the target margin ratio; A603, determine a maintenance power promotion cost of the target DC transmission line, and a third weight corresponding to the maintenance power promotion cost; A604, determine a target influence degree of the target DC transmission line on the stability index of the interconnection line after the line is removed, and a fourth weight corresponding to the target influence degree; the sum of the first weight, the second weight, the third weight and the fourth weight is 1; A605, determine a target removal priority according to the target compensation degree, the first weight, the target margin ratio, the second weight, the maintenance power promotion cost, the third weight, the target influence degree and the fourth weight; the target removal priority is a removal priority corresponding to the target DC transmission line in the J removal priorities.

[0111] In the embodiments of the present application, any one of the J DC transmission lines is selected as the target DC transmission line for analysis.

[0112] The target compensation degree refers to the compensation degree of the target DC transmission line, and its value is directly related to the compensation efficiency of the line in the recovery stage. The lower the compensation degree, the smaller the actual contribution of the line to the continuous compensation, and the more it needs to be removed first. The first weight is an importance coefficient pre-assigned to the target compensation degree, and is used to quantify the influence proportion of the target compensation degree in the calculation of the removal priority.

[0113] The target margin ratio is the ratio of the operating power margin of the target DC transmission line to the maximum power margin. The operating power margin is the difference between the short-time overload upper limit power and the current actual operating power of the line, and the maximum power margin is the difference between the short-time overload upper limit power and the initial power before the fault. The ratio reflects the remaining overload capacity of the line, and the smaller the ratio, the closer the line is to the overload risk. The second weight is an importance coefficient assigned to the target margin ratio, and is used to highlight the influence of the operating safety of the line on the removal sequence.

[0114] The maintenance power promotion cost is the total economic cost generated by the target DC transmission line during the maintenance of the compensation state, including the additional electric energy loss cost and auxiliary service cost caused by the power promotion. The higher the cost, the worse the economy of the continuous compensation. The third weight is an importance coefficient assigned to the maintenance power promotion cost.

[0115] The target influence degree is the change amount of the associated interconnection line stability index after the target DC transmission line is removed. The smaller the change amount, the smaller the disturbance of the removal operation on the stability of the interconnection line. The fourth weight is an importance coefficient assigned to the target influence degree, to ensure that the removal operation does not destroy the system stability.

[0116] In the embodiments of the present application, the sum of the first weight, the second weight, the third weight and the fourth weight is 1.

[0117] In specific embodiments, the target compensation degree of the target DC transmission line is determined, and a first weight corresponding to the target compensation degree is determined, for example, the first weight can be 0.4, indicating that the line with strong compensation ability is preferentially retained.

[0118] The target margin ratio of the operating power margin and the maximum power margin of the target DC transmission line is determined, and a second weight corresponding to the target margin ratio is determined, for example, the second weight can be 0.2, indicating that the overload capacity of the line is considered.

[0119] The maintenance power promotion cost of the target DC transmission line is determined, and a third weight corresponding to the maintenance power promotion cost is determined, for example, the third weight can be 0.2, indicating that the economy is considered. The maintenance power promotion cost can be calculated by the following formula:

[0120] In the above formula, represents the maintenance power promotion cost of the jth DC transmission line; represents the unit price of electric energy; represents the initial time when the jth DC transmission line performs DC compensation; represents the duration of the maintenance power promotion; represents the additional loss power of the jth DC transmission line due to power promotion; represents the auxiliary service cost coefficient; represents the withdrawal power of the jth DC transmission line.

[0121] In the above formula, the unit price of electric energy is a basic parameter for calculating the additional loss cost, which is the market price of unit electric energy, and the unit is yuan / kWh; the additional loss power is the loss power of the line beyond the normal operation due to power promotion, which increases with the promotion of compensation power; the auxiliary service cost coefficient is a coefficient for calculating the cost of auxiliary services (such as dispatching coordination and power regulation), and the unit is yuan / kWh; the withdrawal power is the power value promoted by the line during compensation, that is, the power amplitude that needs to be dropped when the compensation is withdrawn.

[0122] The target influence degree of the target DC transmission line on the stability index of the tie line is determined, and a fourth weight corresponding to the target influence degree is determined, for example, the fourth weight can be 0.4, indicating that the decline of stability caused by withdrawal is avoided. The influence degree of the DC transmission line on the stability index of the tie line can be calculated by the following formula:

[0123] In the above formula, represents the target influence degree; an average tie-line stability index of the entire system after the jth DC transmission line is removed; an average tie-line stability index of the entire system before the jth DC transmission line is removed.

[0124] It should be noted that, a second tie-line stability index of the first DC transmission line in the J DC transmission lines. an average value of the J second tie-line stability indexes of the J DC transmission lines before the jth DC transmission line is removed. an average value of the J second tie-line stability indexes of the J DC transmission lines before the jth DC transmission line is removed.

[0125] The target removal priority can be determined according to the target compensation degree, the first weight, the target margin ratio, the second weight, the maintenance power improvement cost, the third weight, the target influence degree, and the fourth weight, wherein the target removal priority is a removal priority corresponding to the target DC transmission line in the J removal priorities. The removal priority can be calculated by the following formula:

[0126] In the above formula, a removal priority of the jth DC transmission line; a first weight; a compensation degree of the jth DC transmission line; a second weight; an operating power margin of the jth DC transmission line; a maximum power margin of the jth DC transmission line; a third weight; a maintenance power improvement cost of the jth DC transmission line; a fourth weight; an influence degree of the jth DC transmission line on the tie-line stability index.

[0127] The determination of the removal priority takes into account the compensation efficiency, the operating safety, the economic cost, and the system stability, ensures that the influence proportions of the indexes are controllable and the calculation results are objective, and preferentially removes the lines with high risk, high cost, and low contribution, thereby effectively avoiding problems such as line overload, cost waste, or stability damage.

[0128] It can be seen that, by weighting and calculating the revocation priority through multi-dimensional indexes, the scientific quantification of the revocation sequence of the J compensation lines can be realized, the operation safety, compensation efficiency and economic cost can be balanced, the line with high risk, high cost and low contribution can be preferentially revoked, the risk of system power fluctuation or tie-line instability in the revocation process can be effectively avoided, and the smooth transition of the multi-loop DC power transmission system from the compensation state to the normal operation state is ensured.

[0129] S107, performing line revocation on the J DC power transmission lines in descending order of the revocation priority to complete the recovery of the multi-loop DC power transmission system.

[0130] In the embodiment of the application, the line revocation refers to that, for the J DC power transmission lines put into DC compensation, power adjustment instructions are issued by the control system to smoothly recover the lines from the boosted power state in the compensation stage to the initial operation power state before the fault, and the operation of the compensation function of the lines is terminated.

[0131] In specific embodiments, the line revocation is performed on the J DC power transmission lines in descending order of the revocation priority, the line transmission power is gradually reduced from the power in the compensation stage to the initial power before the fault, the power back-off rate needs to be controlled within the safety range allowed by the system, for example, not more than 0.5 MW / s, to prevent the power sudden drop from causing the sending end AC network frequency fluctuation or tie-line power oscillation. After the power back-off of each line is completed and the stable operation state of the line is confirmed through monitoring, the revocation operation of the next line is started in descending order. During this period, the real-time operation parameters of the system are continuously collected. If it is monitored that the system parameters fluctuate beyond the preset safety threshold, the current revocation operation is immediately suspended, and the execution is continued after the system parameters are restored to be stable. When the power back-off and the termination of the compensation function of all the J lines put into compensation are completed, and the overall operation parameters of the system are maintained in the normal rated interval, the recovery of the multi-loop DC power transmission system is completed. Alternatively, while the revocation operation of the J compensation lines is started in descending order of the revocation priority, the generator unit recovery operation is simultaneously started. Among the generator units cut off, the generator units with fast adjustment response speed can be preferentially selected for sequential recovery.

[0132] It can be seen that, by performing the smooth revocation operation line by line in descending order of the revocation priority, the orderly exit of the compensation lines can be realized, the system fluctuation risk caused by unordered revocation or power sudden change can be effectively avoided, the safe and smooth transition of the multi-loop DC power transmission system from the fault compensation state to the normal operation state is ensured, the controllability and reliability of the system fault recovery are significantly improved, and the stable operation of the power grid equipment and power load is ensured.

[0133] According to the embodiment of the present application, the actual total excess energy accumulated during commutation failure of n DC transmission lines in a multi-circuit DC transmission system is obtained; the multi-circuit DC transmission system comprises the n DC transmission lines and m DC transmission lines without commutation failure; J DC transmission lines among the m DC transmission lines are determined to be put into DC compensation according to the actual total excess energy; the sum of compensation energy generated by the J DC transmission lines is determined to obtain actual total compensation energy; machine trip offset energy is determined according to the actual total excess energy and the actual total compensation energy; energy compensation operation is performed on the J DC transmission lines based on the actual total compensation energy, and machine trip operation is performed on the n DC transmission lines according to the machine trip offset energy; recovery operation data of the multi-circuit DC transmission system is obtained, and it is determined whether the recovery operation data meets preset recovery conditions; if yes, J priority revocation priorities of the J DC transmission lines are determined, and priority revocation descending order is determined according to the J priority revocation priorities; the J DC transmission lines are revoked in the priority revocation descending order to complete recovery of the multi-circuit DC transmission system. It can be seen that, through cooperative execution of DC power compensation and machine trip operation, accurate determination of recovery state and ordered revocation of compensation lines, safe and stable recovery of the multi-circuit DC transmission system after commutation failure is realized, and the stability of the system is improved.

[0134] Please refer to Figure 7 , Figure 7 is a structure schematic diagram of a machine trip control optimization device based on DC power compensation provided by the embodiment of the present application, the machine trip control optimization device 700 based on DC power compensation comprises an excess energy calculation module 701, a compensation line determination module 702, a machine trip offset energy calculation module 703, a DC compensation and machine trip control module 704, a system recovery data acquisition module 705, a priority revocation determination module 706, and a line revocation module 707, wherein The excess energy calculation module 701 is configured to obtain actual total excess energy accumulated during commutation failure of n DC transmission lines in a multi-circuit DC transmission system; the multi-circuit DC transmission system comprises the n DC transmission lines and m DC transmission lines without commutation failure; m and n are positive integers; The compensation line determination module 702 is configured to determine J DC transmission lines among the m DC transmission lines to be put into DC compensation according to the actual total excess energy; determine the sum of compensation energy generated by the J DC transmission lines to obtain actual total compensation energy; J is a natural number less than or equal to m; The machine trip offset energy calculation module 703 is configured to determine machine trip offset energy according to the actual total excess energy and the actual total compensation energy; The direct current compensation and generator tripping control module 704 is configured to perform an energy compensation operation on the J direct current transmission lines according to the actual total compensation energy, and perform a generator tripping operation on the n direct current transmission lines according to the generator tripping offset energy; The system recovery data collection module 705 is configured to collect recovery operation data of the multi-loop direct current transmission system, and determine whether the recovery operation data meets a preset recovery condition; The priority canceling determination module 706 is configured to determine J priority canceling priorities of the J direct current transmission lines when the recovery operation data meets the preset recovery condition, and determine a priority canceling descending order according to the J priority canceling priorities. The line canceling module 707 is configured to cancel the J direct current transmission lines in the priority canceling descending order, so as to complete the recovery of the multi-loop direct current transmission system.

[0135] Optionally, in the step of determining the J direct current transmission lines in which direct current compensation is put into operation according to the actual total excess energy, the compensation line determination module 702 is further configured to: obtain an excess energy segmentation table and a maximum energy value of the excess energy segmentation table; the excess energy segmentation table is obtained by dividing energy values into multiple intervals in advance; each interval corresponds to a number of lines in which direct current compensation can be put into operation; determine compensation degrees of the m direct current transmission lines and first tie line stability indexes, to obtain m compensation degrees and m first tie line stability indexes; if the actual total excess energy is less than or equal to the maximum energy value, it is determined that the actual total excess energy is in a target interval corresponding to the actual total excess energy in the excess energy segmentation table; select the J direct current transmission lines from the m direct current transmission lines according to the number of lines in which direct current compensation can be put into operation corresponding to the target interval and the m compensation degrees; J is equal to the number of lines in which direct current compensation can be put into operation corresponding to the target interval; if the actual total excess energy is greater than the maximum energy value, it is determined that a maximum number of lines in which direct current compensation can be put into operation corresponding to a maximum interval in the excess energy segmentation table; select J direct current transmission lines in which direct current compensation can be put into operation from the m direct current transmission lines according to the actual total excess energy, the m compensation degrees and the m first tie line stability indexes, to obtain the J direct current transmission lines; J is greater than or equal to the maximum number of lines in which direct current compensation can be put into operation.

[0136] Optionally, in the determining the compensation degree of the m DC transmission lines and the first tie-line stability index, the compensation line determination module 702 is further configured to: determine the line transient potential energy, the maximum line transient potential energy and the maximum line active power corresponding to the maximum line transient potential energy of the m DC transmission lines during the commutation failure according to a preset line transient potential calculation formula, to obtain m line transient potential energies, m maximum line transient potential energies and m maximum line active powers; determine the m compensation degrees according to the m line transient potential energies; determine the m first tie-line stability indexes according to the m maximum line transient potential energies and the m maximum line active powers.

[0137] Optionally, in the screening J DC transmission lines from the m DC transmission lines according to the actual total excess energy, the m compensation degrees and the m first tie-line stability indexes, to obtain the J DC transmission lines, the compensation line determination module 702 is further configured to: screen h DC transmission lines from the m DC transmission lines according to the m first tie-line stability indexes; the first tie-line stability index corresponding to each DC transmission line in the h DC transmission lines is greater than or equal to a preset first tie-line stability index threshold; h is a positive integer less than or equal to m; screen the J DC transmission lines from the h DC transmission lines; the absolute value of the difference between the sum of the compensation energies of the J DC transmission lines and the actual total excess energy is the smallest, and the sum of the compensation degrees corresponding to the J DC transmission lines is the largest.

[0138] Optionally, the recovery operation data includes: a sliding window average frequency, a frequency standard deviation, a frequency change rate, and J second tie-line stability indexes. In the obtaining the recovery operation data of the multi-circuit DC transmission system, the system recovery data collection module 705 is further configured to: obtain real-time operation parameters of the multi-circuit DC transmission system in a preset recovery time period; the real-time operation parameters include: a time length of a sliding window, an instantaneous frequency set, and a rated frequency; the instantaneous frequency set is the instantaneous frequency of the sliding window at each time in the preset recovery time period; determine the sliding window average frequency and the frequency change rate according to the time length of the sliding window and the instantaneous frequency set; determine a frequency standard deviation according to the set of instantaneous frequencies and the rated frequency; the frequency standard deviation is a dispersion degree of deviation values of each instantaneous frequency in the set of instantaneous frequencies from the rated frequency; determine a second tie-line stability index of the J DC transmission lines, to obtain the J second tie-line stability indexes.

[0139] Optionally, the preset recovery condition includes: an absolute value of a difference between the average frequency in the sliding window and the rated frequency is less than or equal to a preset average frequency threshold, and the frequency standard deviation is less than or equal to a preset frequency standard deviation threshold, and the frequency change rate is less than or equal to a preset upper limit of the frequency change rate, and the J second tie-line stability indexes are all greater than or equal to a preset second tie-line stability index threshold.

[0140] Optionally, in the determination of the J revocation priorities of the J DC transmission lines, the revocation priority determination module 706 is further specifically used for: determine a target compensation degree of a target DC transmission line, and a first weight corresponding to the target compensation degree; the target DC transmission line is any one of the J DC transmission lines; determine a target margin ratio of an operating power margin and a maximum power margin of the target DC transmission line, and a second weight corresponding to the target margin ratio; determine a maintenance power improvement cost of the target DC transmission line, and a third weight corresponding to the maintenance power improvement cost; determine a target influence degree of the target DC transmission line on a tie-line stability index, and a fourth weight corresponding to the target influence degree; a sum of the first weight, the second weight, the third weight and the fourth weight is 1; determine a target revocation priority according to the target compensation degree, the first weight, the target margin ratio, the second weight, the maintenance power improvement cost, the third weight, the target influence degree and the fourth weight; the target revocation priority is a revocation priority corresponding to the target DC transmission line in the J revocation priorities.

[0141] The DC power compensation-based generator tripping control optimization device 700 described in the application can obtain actual total excess energy accumulated during commutation failure of n DC transmission lines in a multi-loop DC transmission system; the multi-loop DC transmission system includes the n DC transmission lines and m DC transmission lines that do not have commutation failure; determine J DC transmission lines among the m DC transmission lines that are put into DC compensation according to the actual total excess energy; determine the sum of compensation energy generated by the J DC transmission lines to obtain actual total compensation energy; determine generator tripping offset energy according to the actual total excess energy and the actual total compensation energy; perform energy compensation operation based on the J DC transmission lines according to the actual total compensation energy, and perform generator tripping operation on the n DC transmission lines according to the generator tripping offset energy; obtain recovery operation data of the multi-loop DC transmission system, and determine whether the recovery operation data meets a preset recovery condition; if yes, determine J generator tripping priority cancellations of the J DC transmission lines, and determine generator tripping priority cancellation descending order according to the J generator tripping priority cancellations; cancel the J DC transmission lines in the generator tripping priority cancellation descending order to complete recovery of the multi-loop DC transmission system. It can be seen that, through cooperative execution of DC power compensation and generator tripping operation, accurate determination of recovery state and orderly cancellation of compensation lines, safe and smooth recovery of the multi-loop DC transmission system after commutation failure is realized, and the stability of the system is improved.

[0142] See Figure 8 , Figure 8 is a structural schematic diagram of an electronic device provided by an embodiment of the application. The electronic device can include a processor, a memory, a communication interface, and one or more programs. The processor, the memory, and the communication interface can be connected to each other through a bus. The one or more programs are stored in the memory and are configured to be executed by the processor. In the embodiment of the application, the program includes instructions for performing the following steps: obtain actual total excess energy accumulated during commutation failure of n DC transmission lines in a multi-loop DC transmission system; the multi-loop DC transmission system includes the n DC transmission lines and m DC transmission lines that do not have commutation failure; m and n are positive integers; determine J DC transmission lines among the m DC transmission lines that are put into DC compensation according to the actual total excess energy; determine the sum of compensation energy generated by the J DC transmission lines to obtain actual total compensation energy; J is a natural number less than or equal to m; determine generator tripping offset energy according to the actual total excess energy and the actual total compensation energy; perform energy compensation operation based on the J DC transmission lines according to the actual total compensation energy, and perform generator tripping operation on the n DC transmission lines according to the generator tripping offset energy; acquire recovery operation data of the multi-loop DC power transmission system, and determine whether the recovery operation data meets a preset recovery condition; If yes, determine J priorities of the J DC power transmission lines, and determine a priority descending order according to the J priorities; perform line cancellation on the J DC power transmission lines in the priority descending order to complete recovery of the multi-loop DC power transmission system.

[0143] The electronic device described in the present application can acquire actual total excess energy accumulated during commutation failure of n DC power transmission lines in a multi-loop DC power transmission system; the multi-loop DC power transmission system includes the n DC power transmission lines and m DC power transmission lines that do not have commutation failure; determine J DC power transmission lines among the m DC power transmission lines that are put into DC compensation according to the actual total excess energy; determine a sum of compensation energy generated by the J DC power transmission lines to obtain actual total compensation energy; determine machine tripping offset energy according to the actual total excess energy and the actual total compensation energy; perform energy compensation based on the J DC power transmission lines according to the actual total compensation energy, and perform machine tripping operation on the n DC power transmission lines according to the machine tripping offset energy; acquire recovery operation data of the multi-loop DC power transmission system, and determine whether the recovery operation data meets a preset recovery condition; if yes, determine J priorities of the J DC power transmission lines, and determine a priority descending order according to the J priorities; perform line cancellation on the J DC power transmission lines in the priority descending order to complete recovery of the multi-loop DC power transmission system. It can be seen that through the cooperative execution of DC power compensation and machine tripping operation, accurate determination of the recovery state and orderly cancellation of the compensation lines, safe and smooth recovery of the multi-loop DC power transmission system after commutation failure is realized, and the stability of the system is improved.

[0144] The embodiment of the present application further provides a computer readable storage medium, wherein the computer readable storage medium stores a computer program for electronic data exchange, and the computer program causes a computer to execute part or all steps of any method described in the above method embodiments, and the computer includes the electronic device.

[0145] The embodiment of the present application further provides a computer program product, and the computer program product includes a non-transitory computer readable storage medium storing a computer program, and the computer program is operable to cause a computer to execute part or all steps of any method described in the above method embodiments. The computer program product can be a software installation package, and the computer includes the electronic device.

[0146] Those skilled in the art can understand that all or part of the processes in the above-mentioned method embodiments can be implemented by a computer program instructing relevant hardware, and the program can be stored in a computer readable storage medium. When the program is executed, the processes of the above-mentioned method embodiments can be included. The storage medium includes ROM, RAM, magnetic disk or optical disk, and various storage media that can store program codes.

[0147] The steps of the methods or algorithms described in the embodiments of the present application can be implemented in the form of hardware or by a processor executing software instructions. The software instructions can be composed of corresponding software modules, and the software modules can be stored in RAM, flash memory, ROM, EPROM, electrically EPROM (EEPROM), register, hard disk, mobile hard disk, CD-ROM or any other form of storage medium well known in the art. An exemplary storage medium is coupled to the processor, so that the processor can read information from the storage medium and write information to the storage medium. Of course, the storage medium can also be an integral part of the processor. The processor and the storage medium can be located in an ASIC. In addition, the ASIC can be located in a terminal device or a management device. Of course, the processor and the storage medium can also exist as discrete components in the terminal device or the management device.

[0148] Those skilled in the art should be aware that, in one or more examples described above, the functions described in the embodiments of the present application can be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented by software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When loaded and executed on a computer, the computer program instructions generate, in whole or in part, the processes or functions described in the embodiments of the present application. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions can be stored in a computer-readable storage medium or transferred from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transferred from one website, computer, server, or data center to another website, computer, server, or data center through a wired (for example, coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (for example, infrared, wireless, microwave, etc.) manner. The computer-readable storage medium can be any available medium accessible by a computer or a data storage device such as a server, data center, etc. integrated with one or more available media. The available medium can be a magnetic medium (for example, a floppy disk, a hard disk, a magnetic tape), an optical medium (for example, a digital video disc (DVD)), or a semiconductor medium (for example, a solid state disk (SSD)), etc.

[0149] The various modules / units included in the various devices and products described in the above embodiments can be software modules / units or hardware modules / units, or partially software modules / units and partially hardware modules / units. For example, for the various devices and products applied to or integrated into a chip, the various modules / units included therein can all be implemented in the form of hardware such as circuitry, or at least some of the modules / units can be implemented in the form of software programs running on a processor integrated in the chip, and the remaining (if any) modules / units can be implemented in the form of hardware such as circuitry; for the various devices and products applied to or integrated into a chip module, the various modules / units included therein can all be implemented in the form of hardware such as circuitry, and different modules / units can be located in the same component (e.g., a chip, a circuit module, etc.) or different components of the chip module, or at least some of the modules / units can be implemented in the form of software programs running on a processor integrated in the chip module, and the remaining (if any) modules / units can be implemented in the form of hardware such as circuitry; for the various devices and products applied to or integrated into a terminal device, the various modules / units included therein can all be implemented in the form of hardware such as circuitry, and different modules / units can be located in the same component (e.g., a chip, a circuit module, etc.) or different components of the terminal device, or at least some of the modules / units can be implemented in the form of software programs running on a processor integrated in the terminal device, and the remaining (if any) modules / units can be implemented in the form of hardware such as circuitry.

[0150] The above detailed description of the specific implementation of the embodiments of the present application has further explained the purposes, technical solutions, and beneficial effects of the embodiments of the present application. It should be understood that the above description is only a specific implementation of the embodiments of the present application and is not intended to limit the protection scope of the embodiments of the present application. Any modification, equivalent replacement, improvement, etc. made on the basis of the technical solutions of the embodiments of the present application shall be included in the protection scope of the embodiments of the present application.

Claims

1. A method for optimizing tripping control based on DC power compensation, characterized in that, The method includes: Obtain the actual excess total energy accumulated during the commutation failure period of n DC transmission lines in a multi-circuit DC transmission system; the multi-circuit DC transmission system includes the n DC transmission lines and m DC transmission lines that did not experience commutation failure; m and n are positive integers; Based on the actual total excess energy, determine J DC transmission lines among the m DC transmission lines that will be put into DC compensation; determine the sum of the compensation energy generated by the J DC transmission lines to obtain the actual total compensation energy; J is a natural number less than or equal to m; The cut-off offset energy is determined based on the actual total excess energy and the actual total compensation energy. Based on the actual total compensation energy, energy compensation operations are performed on the J DC transmission lines, and based on the tripping offset energy, tripping operations are performed on the n DC transmission lines; Acquire the recovery operation data of the multi-circuit DC transmission system and determine whether the recovery operation data meets the preset recovery conditions; If so, determine the J cancellation priorities of the J DC transmission lines, and determine the descending order of cancellation priorities based on the J cancellation priorities; The J DC transmission lines are cancelled in descending order of cancellation priority to complete the restoration of the multi-circuit DC transmission system.

2. The method as described in claim 1, characterized in that, The step of determining J DC transmission lines among the m DC transmission lines to be equipped with DC compensation based on the actual total excess energy includes: Obtain the excess energy segmentation table and the maximum energy value of the excess energy segmentation table; the excess energy segmentation table is composed of multiple intervals divided in advance according to the size of the energy value; each interval corresponds to the number of lines that can be put into DC compensation. The compensation degree and the stability index of the first tie line of the m DC transmission lines are determined to obtain m compensation degrees and m stability indices of the first tie line; If the actual total excess energy is less than or equal to the maximum energy value, then the target interval corresponding to the actual total excess energy in the excess energy segmentation table is determined. J DC transmission lines are selected from the m DC transmission lines based on the number of DC compensation lines available for the target interval and the m compensation degrees; J is equal to the number of DC compensation lines available for the target interval. If the actual total excess energy is greater than the maximum energy value, then determine the maximum number of DC compensation lines that can be put into operation for the largest interval in the excess energy segmentation table. Based on the actual excess total energy, the m compensation degrees, and the m first tie line stability indicators, J DC transmission lines that can be put into DC compensation are selected from the m DC transmission lines to obtain the J DC transmission lines; J is greater than or equal to the maximum number of lines that can be put into operation.

3. The method as described in claim 2, characterized in that, The determination of the compensation degree and the stability index of the first tie line for the m DC transmission lines, resulting in m compensation degrees and m first tie line stability indices, includes: Based on the preset formula for calculating the transient potential energy of the line, the transient potential energy of the line, the maximum transient potential energy of the line, and the maximum active power of the line corresponding to the maximum transient potential energy are determined for the m DC transmission lines during the commutation failure period, thus obtaining m transient potential energies of the line, m maximum transient potential energies of the line, and m maximum active power of the line. The m compensation degrees are determined based on the transient dynamic energy of the m lines; The stability indices of the m first tie lines are determined based on the transient dynamic energy and active power of the m maximum lines.

4. The method as described in claim 3, characterized in that, The process of selecting J DC transmission lines from the m DC transmission lines that can be put into DC compensation based on the actual total excess energy, the m compensation degrees, and the m first tie-line stability indicators, to obtain the J DC transmission lines, includes: Based on the m first tie line stability indices, h DC transmission lines are selected from the m DC transmission lines; the first tie line stability index corresponding to each of the h DC transmission lines is greater than or equal to a preset first tie line stability index threshold; h is a positive integer less than or equal to m; J DC transmission lines are selected from the h DC transmission lines; the absolute value of the difference between the sum of the compensation energy of the J DC transmission lines and the actual total excess energy is the smallest, and the sum of the compensation degree corresponding to the J DC transmission lines is the largest.

5. The method according to any one of claims 1-4, characterized in that, The restored operation data includes: sliding window average frequency, frequency standard deviation, frequency change rate, and J second tie-line stability indicators; The acquisition of the restored operation data of the multi-circuit DC transmission system includes: The real-time operating parameters of the multi-circuit DC transmission system are obtained within a preset recovery time period; the real-time operating parameters include: the time length of the sliding window, the instantaneous frequency set, and the rated frequency; the instantaneous frequency set is the instantaneous frequency of the sliding window at each moment within the preset recovery time period; The average frequency and the rate of change of the sliding window are determined based on the time length of the sliding window and the instantaneous frequency set; The frequency standard deviation is determined based on the instantaneous frequency set and the rated frequency; the frequency standard deviation is the degree of dispersion of the deviation value between each instantaneous frequency in the instantaneous frequency set and the rated frequency. The stability index of the second tie line of the J DC transmission lines is determined to obtain the J second tie line stability indices.

6. The method as described in claim 5, characterized in that, The preset recovery conditions include: the absolute value of the difference between the average frequency of the sliding window and the rated frequency is less than or equal to a preset average frequency threshold, and the frequency standard deviation is less than or equal to a preset frequency standard deviation threshold, and the frequency change rate is less than or equal to a preset upper limit of the frequency change rate, and all J second tie line stability indices are greater than or equal to preset second tie line stability index thresholds.

7. The method according to any one of claims 1-4, characterized in that, The determination of the J cancellation priorities for the J DC transmission lines includes: Determine the target compensation degree of the target DC transmission line and the first weight corresponding to the target compensation degree; the target DC transmission line is any one of the J DC transmission lines. Determine the target margin ratio of the operating power margin to the maximum power margin of the target DC transmission line, and the second weight corresponding to the target margin ratio; Determine the maintenance power enhancement cost of the target DC transmission line, and the third weight corresponding to the maintenance power enhancement cost; Determine the target impact degree of the removal of the target DC transmission line on the stability index of the tie line, and the fourth weight corresponding to the target impact degree; the sum of the first weight, the second weight, the third weight and the fourth weight is 1; The target cancellation priority is determined based on the target compensation degree, the first weight, the target margin ratio, the second weight, the maintenance power enhancement cost, the third weight, the target impact degree, and the fourth weight; the target cancellation priority is the cancellation priority corresponding to the target DC transmission line among the J cancellation priorities.

8. A switching control optimization device based on DC power compensation, characterized in that, The DC power compensation-based tripping control optimization device includes: an excess energy calculation module, a compensation line determination module, a tripping offset energy calculation module, a DC compensation and tripping control module, a system recovery data acquisition module, a cancellation priority determination module, and a line cancellation module, wherein... The excess energy calculation module is used to obtain the actual total excess energy accumulated during the commutation failure period of n DC transmission lines in a multi-circuit DC transmission system; the multi-circuit DC transmission system includes the n DC transmission lines and m DC transmission lines that have not experienced commutation failure; m and n are positive integers; The compensation line determination module is used to determine J DC transmission lines among the m DC transmission lines that will be put into DC compensation based on the actual total excess energy; and to determine the sum of the compensation energy generated by the J DC transmission lines to obtain the actual total compensation energy; J is a natural number less than or equal to m; The cut-off offset energy calculation module is used to determine the cut-off offset energy based on the actual total excess energy and the actual total compensation energy. The DC compensation and tripping control module is used to perform energy compensation operations on the J DC transmission lines based on the actual total compensation energy, and to perform tripping operations on the n DC transmission lines based on the tripping offset energy; The system recovery data acquisition module is used to acquire the recovery operation data of the multi-circuit DC transmission system and determine whether the recovery operation data meets the preset recovery conditions. The cancellation priority determination module is used to determine J cancellation priorities for the J DC transmission lines when the restored operation data meets the preset restoration conditions, and to determine the descending order of cancellation priorities based on the J cancellation priorities; The line cancellation module is used to cancel the J DC transmission lines in descending order of cancellation priority in order to complete the restoration of the multi-circuit DC transmission system.

9. An electronic device, characterized in that, include: Processor, memory, communication interface, and one or more programs; The one or more programs are stored in the memory and configured to be executed by the processor, the programs including instructions for performing the steps of the method as described in any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, the computer program including program instructions that, when executed by a processor, cause the processor to perform the method as described in any one of claims 1-7.

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