Alternating current filter priority input / output selection method and system

Abstract

The invention provides an AC filter priority input / exit selection method and system, and relates to the technical field of DC power transmission. Priority input / exit of part of filters is realized through priority updating logic, and input / exit times of the same type of AC filters are averaged through circularly traversed filter input / exit selection logic. On the premise that direct-current power rising and falling modulation is not affected and the average number of times of input / exit of the alternating-current filter is guaranteed, flexible setting and adjustment of the input / exit priority of the alternating-current filter are achieved, the use frequency of hidden danger or abnormal equipment is controlled, the number of times of forced outage of direct-current equipment is reduced, maintenance of in-operation engineering is facilitated, and the service life of the direct-current equipment is prolonged. And the direct current availability is ensured.

Description

Technical Field

[0001] The present invention belongs to the technical field of conventional direct current power transmission and high voltage direct current power transmission, and more specifically, relates to an AC filter activation / deactivation control method and system. Background Art

[0002] In the field of conventional DC transmission and high-voltage DC transmission, the reactive power control of the DC system sending and receiving ends is mainly achieved through the input / output control of AC filters to maintain the reactive power balance of the AC and DC systems. The reactive power control function uses the corresponding number of AC filters according to the preset reactive strategy, system voltage, current DC power level and other criteria. The order of the number of different types of AC filters to be put into use follows the reactive strategy table. There is no fixed order for the input / output selection of the same type of AC filters. It is only necessary to ensure that the number of input / output times of each AC filter is basically consistent.

[0003] During the operation and maintenance of the DC system, special situations may occur where some AC filter primary equipment is found to have abnormalities or hidden dangers through countermeasures / inspections. In order to avoid forced shutdown of the DC, it is necessary to reduce or limit the use of the corresponding equipment during the DC operation. For AC filters, prohibiting the use of AC filters will affect the reactive power strategy, which in turn affects the power limit of the DC system and even causes power reduction. Therefore, there is a need to develop a flexible AC filter entry / exit control strategy. Summary of the invention

[0004] In order to solve the deficiencies in the prior art, the present invention provides an AC filter priority input / output selection method and system, which can realize the flexible setting and adjustment of the input / output priority of the AC filter without affecting the DC power up / down modulation and ensuring the average number of AC filter input / output times.

[0005] To achieve the above object, the present invention adopts the following scheme:

[0006] A first aspect of the present invention provides an AC filter priority input / output selection method for DC power transmission reactive power control, comprising:

[0007] generating an initial priority for each AC filter of the same type of AC filters, and further generating an internal availability state of the AC filter in a set of AC filters of the same type;

[0008] If there is an AC filter of the same type with a valid internal available state, all initial priorities of the filters of this type are given to the selection priority, otherwise the selection priority of the filters of this type is updated according to the set rules;

[0009] Based on the selection priority of each AC filter, a logically available state of each AC filter is generated, and based on the logically available state of each AC filter, a filter input / exit selection logic is used to generate a selection channel sequence number to realize a cyclic traversal;

[0010] The AC filter is selected to be enabled / disabled based on the selected channel number and the available status of the primary device.

[0011] Preferably, generating an initial priority for each AC filter of the same type of AC filters comprises:

[0012] According to the priority control enable signal state, the initial priority of the AC filter is set to one of priority 1 or priority 2. Priority 1 and priority 2 are two sets. The initial priority of the AC filter is a specific value of priority 1 or priority 2. The value of priority 1 is greater than the threshold value, and the value of priority 2 does not exceed the threshold value.

[0013] Preferably, further generating the internal available state of the AC filter in a set of AC filters of the same type comprises:

[0014] When the priority control enable signal of the AC filter is invalid, the initial priority of the AC filter is set to a priority level 1 higher than the threshold value, and further, if the primary device of the AC filter is available, the internal available state of the AC filter is valid; if the primary device of the AC filter is unavailable, the internal available state of the AC filter is invalid;

[0015] When the priority control enable signal of the AC filter is effective, the initial priority of the AC filter is set to priority 2 which is lower than the threshold value, and the internal availability state of the AC filter is invalid regardless of whether the primary device of the AC filter is available.

[0016] Preferably, updating the selection priority of the filter according to the set rules includes:

[0017] If the priority control enable of the AC filter is effective, the internal available states of the same type of AC filters are invalid and the current selection priority of the AC filter is not higher than the set threshold, the selection priority of the AC filter is increased; otherwise, the selection priority of the AC filter is maintained.

[0018] Preferably, during the operation and maintenance of the DC system, if a special situation occurs in which a primary device of a certain AC filter has an abnormality or hidden danger, it is necessary to limit the use of the device without affecting the power upper limit of the DC system during operation, and the priority control of the AC filter is enabled separately to make the priority 2 of the AC filter effective;

[0019] After being put into operation, when the primary device availability status of any AC filter of the same type as the AC filter is valid, the selection priority of the AC filter does not meet the threshold condition, so as to prevent the AC filter from being selected as the next group of filters to be put into operation;

[0020] When the available status of the primary devices of the same type of AC filter as the AC filter is invalid, the selection priority of the AC filter is updated according to the set rules until the selection priority meets the threshold condition, and the AC filter Ax is selected as the next group of filters to be put into use;

[0021] When the AC filter is selected as the next set of filters to be put into operation, and the primary device availability status of any AC filter of the same type is restored to be valid, the selection priority of the AC filter is reset according to the set rules, and it is no longer selected as the next set of filters to be put into operation.

[0022] Preferably, when priority control of multiple AC filters enables input, and the available states of the primary devices of the same type of AC filters are all invalid, the selection priorities of the multiple AC filters enabled by priority control are synchronously updated according to the set rules until one of them is selected as the next group of filters to be put into operation;

[0023] According to the setting difference of priority 2, priority control enables multiple AC filters to be opened and selected in sequence;

[0024] After the selection is completed, the remaining filter selection priorities maintain their current state and the opening order corresponding to the priority 2 setting does not change.

[0025] Preferably, generating the logically available state of each AC filter based on the selection priority of each AC filter comprises:

[0026] The selection priority of each AC filter is judged by the threshold condition to obtain the priority selection enable of the corresponding filter. The primary device availability status of each AC filter and the priority selection enable of the corresponding filter are subjected to AND logic operation, and the operation results are respectively used as the logical availability status of the corresponding filter.

[0027] Preferably, the method of using filter input / exit selection logic to generate a selection channel sequence number based on the available state of each AC filter logic to implement cyclic traversal includes:

[0028] The filter input / exit selection logic takes all the logically available states of the same type of AC filters as input, and takes the selected channel number and the logically available state corresponding to the selected channel as output;

[0029] If the logic available state of the selected channel is valid, the filter entry / exit selection logic maintains the currently selected channel;

[0030] If the logically available state of the selected channel is invalid, the filter input / exit selection logic selects the next channel and detects its logically available state by accumulating the counter; if the filter input / exit selection logic selects the maximum output channel and the logically available state is invalid, the counter state is reset, and the selected channel is updated to channel 1 to achieve loop traversal.

[0031] Preferably, the AC filter selected for activation / deactivation based on the selected channel sequence number and the available status of the primary device comprises:

[0032] If the channel where the AC filter is located is the channel selected by the filter activation / deactivation selection logic, the AC filter of this type is allowed to be activated / deactivated, and the primary device status of the AC filter is valid, then the AC filter becomes the filter selected for activation / deactivation among the AC filters of the same type.

[0033] The second aspect of the present invention provides an AC filter priority input / exit selection system, which runs the AC filter priority input / exit selection method, including: an internal available state signal update logic module, a selection priority update logic module, a loop traversal filter selection logic module and a filter input selection logic module;

[0034] The internal available state signal update logic module generates an initial priority for each AC filter of the same type of AC filters, and further generates an internal available state of the AC filter in a set of AC filters of the same type;

[0035] The priority update logic module is selected to update the internal available state generated by the logic module according to the internal available state signal, and configure the selection priority of the AC filter;

[0036] The filter selection logic module of the loop traversal generates a logically available state of each AC filter based on the selection priority of each AC filter, and uses the filter input / exit selection logic to generate a selection channel sequence number based on the logically available state of each AC filter to realize the loop traversal;

[0037] The filter activation / deactivation selection logic module selects the channel number and the available status of the primary device to select the AC filter to be activated / deactivated.

[0038] Compared with the prior art, the beneficial effects of the present invention include at least: proposing a method for selecting the priority input / output of an AC filter, which can flexibly set and adjust the input / output priority of the AC filter without affecting the DC power up / down modulation and ensuring an average number of input / output times of the AC filter, control the frequency of use of equipment with hidden dangers or abnormalities, reduce the number of forced shutdowns of DC equipment, facilitate the maintenance of in-service projects, and ensure the DC availability. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a schematic diagram of an internal available state signal update logic of the present invention, and the meanings of the variables in the diagram are shown in Table 1;

[0040] Figure 2 This is a logic diagram of selecting priority update of the present invention, and the meanings of the variables in the diagram are shown in Table 1;

[0041] Figure 3 This is a schematic diagram of filter selection logic for cyclic traversal of the present invention, and the meanings of the variables in the figure are shown in Table 1;

[0042] Figure 4 This is a filter input selection logic diagram of the present invention. The meanings of the variables in the diagram are shown in Table 1. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The described embodiments are only embodiments of a part of the present invention, not all embodiments. Based on the spirit of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of the present invention.

[0044] Embodiment 1 of the present invention provides an AC filter priority input / output selection method for DC power transmission reactive power control, which implements priority input / output of some filters through priority update logic, and implements the average input / output times of the same type of AC filters through cyclic traversal filter input / output selection logic.

[0045] The control area of ​​the applicable scenario of the present invention may include multiple types of filters, and each type of filter may include multiple AC filters. For example, the control area includes: M TYPE_A type AC filters and N TYPE_B type AC filters. It can be understood that the two types, M and N, are only an example but not a limiting implementation method. In engineering practice, the use of more types of filters, or only one type of filter on site, falls within the scope of the present invention.

[0046] M TYPE_A type AC filters are represented by AC filter Ax, where x=1, 2, ..., M; N TYPE_B type filters are represented by AC filter By, where y=1, 2, ..., N. It is worth noting that in order to clearly introduce the core concept of the present invention, involving the priority input / output selection of the same type of AC filters, only M TYPE_A type AC filters are used to introduce the technical solution as AC filter Ax, and the operation of N TYPE_B type AC filters is similar. The input and output logics are similar, and only the input logic is introduced. The input logic signal is replaced by the exit logic signal to obtain the exit selection method.

[0047] The AC filter priority input / output selection method specifically comprises the following steps:

[0048] Step 1: generating an initial priority for each AC filter of the same type, and further generating an internal availability state of the AC filter in a set of AC filters of the same type.

[0049] Preferably but not restrictively, according to the priority control enable signal state, the initial priority of the AC filter is set to one of priority 1 or priority 2, priority 1 and priority 2 are two sets, the initial priority of the AC filter is a specific value in priority 1 or priority 2, the value of priority 1 is greater than the threshold value, and the value of priority 2 does not exceed the threshold value.

[0050] If the initial priority of the AC filter is higher than the set threshold value and the primary device is available, the AC filter is in an available state within the set of AC filters of the same type, and the internal available state of the AC filter is set to valid; if it is not higher than the set threshold value, the AC filter is in an unavailable state within the set of AC filters of the same type, and the internal available state of the AC filter is set to invalid.

[0051] More specifically, when the priority control enable signal of the AC filter is invalid, the initial priority of the AC filter is set to priority 1 which is higher than the threshold value. Further, if the primary device of the AC filter is available, the internal available state of the AC filter is valid; if the primary device of the AC filter is unavailable, the internal available state of the AC filter is invalid.

[0052] When the priority control enable signal of the AC filter is effective, the initial priority of the AC filter is set to priority 2 which is lower than the threshold value, and the internal availability state of the AC filter is invalid regardless of whether the primary device of the AC filter is available.

[0053] That is to say, when the priority control of one or several filters is enabled, the filter is set to not be prioritized, so that other enabled but not yet enabled filters can be prioritized; when no filter's priority control is enabled, there is no priority between filters; it supports none of the priority control enabled at the same time, but does not support all of the priority control enabled at the same time.

[0054] Thus, by controlling the priority enable signal and setting the threshold value, the initial configuration of whether the AC filter is put into use in the subsequent steps is realized in the initial priority setting link. It can be understood that the priority 2 not higher than the threshold value can be updated according to the priority selection function in the subsequent steps.

[0055] Further preferably but not limiting, Figure 1 This is a schematic diagram of an internal available state signal update logic according to an embodiment of the present application, wherein:

[0056] The Ax_ENA signal represents the priority control enable state of the AC filter Ax, that is, A1_ENA, A2_ENA...AM_ENA represent the priority control enable states corresponding to the AC filter 1 to the AC filter M respectively; for example but not limited to, Ax_ENA=1 represents that the priority control enable state of the AC filter Ax is valid; correspondingly, Ax_ENA=0 represents that the priority control enable state of the AC filter Ax is invalid.

[0057] Ax_PRI_th represents a set threshold, which is used for comparison with the priority of the AC filter Ax, including comparison with the initial priority or the selected priority, and then obtaining a comparison result of exceeding the threshold value or not exceeding the threshold value; for example but not limited to, Ax_PRI_th=0, it can be determined whether the current initial priority or the selected priority of the AC filter Ax is greater than 0.

[0058] The Ax_PRI_1 signal represents the initial priority of the AC filter Ax, that is, A1_PRI_1, A2_PRI_1, ... AM_PRI_1 respectively represent the initial priorities corresponding to the AC filter 1 to the AC filter M. The initial priorities of the AC filter include priority 1 and priority 2; wherein priority 1 and priority 2 are two sets, and the initial priority of the AC filter Ax is a specific value of priority 1 or priority 2.

[0059] The Ax_AVAIL signal represents the primary device availability status of the AC filter Ax, that is, A1_AVAIL, A2_AVAIL...AM_AVAIL represent the primary device availability status of filters A1 to AM respectively; multiple primary device availability statuses can be valid at the same time; for example but not limited to, Ax_AVAIL=1 indicates that the primary device availability status of the AC filter Ax is valid; correspondingly, Ax_AVAIL=0 indicates that the primary device availability status of the AC filter Ax is invalid.

[0060] The Ax_AVAIL_1 signal represents the internal availability status of the AC filter Ax, that is, A1_AVAIL_1, A2_AVAIL_1...AM_AVAIL_1 respectively represent whether it is in an available state within the TYPE_A filter set; for example but not limited to, Ax_AVAIL_1=1, indicating that the AC filter Ax in the TYPE_A filter set is in an available state; correspondingly, Ax_AVAIL_1=0, indicating that the AC filter Ax in the TYPE_A filter set is in an unavailable state.

[0061] Updating the internal available state signal includes: setting the initial priority of the AC filter according to the priority control enable state, and updating the internal available state signal in combination with the available state of each AC filter primary device in the same type AC filter set.

[0062] Among them, setting the initial priority of the AC filter Ax includes: when the priority control enable Ax_ENA is valid, setting the initial priority Ax_PRI_1 of the AC filter Ax to priority 1, for example but not limited to, Ax_PRI_1=x, that is, setting the initial priority of the AC filter in the TYPE_A filter set to its number, which is a positive integer greater than the Ax_PRI_th threshold value of 0; correspondingly, when the priority control enable Ax_ENA is invalid, setting the initial priority Ax_PRI_1 of the AC filter x to priority 2, Ax_PRI_1=1-x, which is an integer not exceeding the Ax_PRI_th threshold value of 0.

[0063] After the initial priority Ax_PRI_1 of the AC filter Ax is compared with the set threshold Ax_PRI_th, it is then ANDed with the primary device availability state Ax_AVAIL of the AC filter Ax, and the operation result is used as the internal availability state Ax_AVAIL_1 of the AC filter Ax. This means that after comparing with the threshold value, if the initial priority Ax_PRI_1 of the AC filter Ax is high enough and the primary device of the AC filter Ax is available, the AC filter Ax in the TYPE_A filter set is in an available state; if the initial priority Ax_PRI_1 of the AC filter Ax is not high enough, or the primary device of the AC filter Ax is unavailable, the AC filter Ax in the TYPE_A filter set is in an unavailable state.

[0064] Step 2: If there is an AC filter of the same type with a valid internal available state, all initial priorities of the filters of this type are given to the selection priority, otherwise the selection priority of the filters of this type is updated according to the set rules.

[0065] Preferably but not restrictively, if there is an AC filter with a valid internal available state among the same type of AC filters, the initial priority of the filter of this type is output as the filter logic selection priority; when the internal available states of the same type of AC filters are all invalid, the filter logic selection priority is synchronously judged and updated according to the following rules:

[0066] If the priority control of the AC filter is enabled, the internal available states of the same type of AC filters are invalid, and the current selection priority of the AC filter is not higher than the set threshold, the selection priority of the AC filter is updated according to the set rules, for example but not limited to, the selection priority of the AC filter is updated in a manner of increasing the selection priority.

[0067] Further preferably but not limiting, Figure 2 This is a logic diagram for selecting priority updates according to an embodiment of the present application, wherein:

[0068] The Ax_PRI_2 signal represents the selection priority corresponding to the AC filter Ax, that is, A1_PRI_2, A2_PRI_2...AM_PRI_2 represent the selection priorities corresponding to the AC filter 1 to the AC filter M, respectively, and are used to indicate whether the AC filter Ax can be opened and the optional opening order in the TYPE_A filter. If the threshold condition is met, it means that it can be opened, and the value indicates the optional opening order; if the threshold condition is not met, it means that it cannot be opened. Among them, multiple selection priorities can meet the threshold condition at the same time. Before enabling the update logic, the initial value of Ax_PRI_2 is all assigned to 0.

[0069] The Ax_AVAIL_2 signal represents the logical availability state of the AC filter Ax, that is, A1_AVAIL_2, A2_AVAIL_2...AM_AVAIL_2 represent the logical availability states of AC filter 1 to AC filter M respectively, and multiple logical availability states can be valid at the same time; for example but not limited to, Ax_AVAIL_2=1 indicates that the logical availability state of the AC filter Ax is valid, the primary device of the AC filter Ax is available and the selection priority Ax_PRI_2 shows that it can be opened; otherwise Ax_AVAIL_2=0 indicates that the logical availability state of the AC filter Ax is invalid.

[0070] Updating the selection priority includes: if there is an AC filter of the same type with a valid internal available state, giving all initial priorities of the AC filter of this type to the selection priority; otherwise, updating the selection priority of the AC filter of this type according to the set rules, and selecting the next group of AC filters to be put into use.

[0071] Taking the TYPE_A filter as an example, when the internal available state of at least one AC filter in the TYPE_A filter set is valid, the initial priority Ax_PRI_1 of all AC filters Ax is output as the filter logic selection priority Ax_PRI_2; when the internal available state Ax_AVAIL_1 of any AC filter Ax in the TYPE_A filter set is invalid, the filter logic selection priority is synchronously judged and updated according to the following rules:

[0072] When the priority control enable Ax_ENA of each AC filter Ax takes effect, the logical available state Ax_AVAIL_2 of the TYPE_A filter is invalid, and the selection priority Ax_PRI_2 of the AC filter Ax does not reach the threshold condition, the selection priority of the AC filter Ax is updated in a manner of increasing the selection priority according to the set rule, for example but not limited to, increasing the value of the selection priority Ax_PRI_2 by 1; when the above conditions are not met at the same time, the current selection priority of the AC filter Ax is maintained. This means that after the priority control enable Ax_ENA starts the priority control of each AC filter Ax, if the logical available state Ax_AVAIL_2 of each AC filter Ax is invalid and the selection priority Ax_PRI_2 of each AC filter Ax is lower than the threshold, the selection priority Ax_PRI_2 of the AC filter Ax is attempted to be increased, so that at least one AC filter in the TYPE_A filter set has a selection priority that exceeds the threshold, and its logical available state is changed from invalid to valid, and the next group of AC filters to be put into use is selected.

[0073] It is worth noting that usually the priority control enable is not fully activated. There is at least one AC filter in the TYPE_A filter set whose internal available state Ax_AVAIL_1 is valid, which makes all initial priorities Ax_PRI_1 give the selection priority Ax_PRI_2; if all internal available states Ax_AVAIL_1 are invalid, all Ax_PRI_2 are 0, and it will not affect the function. The reason is that initially all Ax_AVAIL_1 are invalid, which means that the available state of the filter device that has not been activated is unavailable. At this time Figure 2 The selection priority Ax_PRI_2 is all 0, and then the priority control enables the selection priority Ax_PRI_2 to be updated to 1, then all filters will meet the priority input conditions, which means that the priority control is not actually effective, but it does not affect the filter input selection. Until there is a group of filters that are not enabled by the priority control and are available, the corresponding internal available state Ax_AVAIL_1 is valid, and other filters are given the selection priority Ax_PRI_2 according to the initial priority Ax_PRI_1.

[0074] During the operation and maintenance of the DC system, if there is a special situation where the primary equipment of the AC filter Ax is abnormal or has hidden dangers, and it is necessary to limit the use of the equipment without affecting the power upper limit of the DC system during operation, the operation and maintenance personnel can separately enable the priority control Ax_ENA of the AC filter Ax to make the priority 2 of the AC filter Ax effective.

[0075] After being put into operation, when the primary device availability status of any AC filter of the same type as the AC filter Ax is valid, the selection priority Ax_PRI_2 of the AC filter Ax does not meet the threshold condition, so as to prevent the AC filter Ax from being selected as the next group of filters to be put into operation;

[0076] When the available status of the primary devices of the TYPE_A type AC filter of the same type as the AC filter Ax is invalid, the selection priority Ax_PRI_2 of the AC filter Ax is updated according to the set rules until the selection priority meets the threshold condition, and the AC filter Ax is selected as the next group of filters to be put into use;

[0077] When AC filter Ax is selected as the next set of filters to be put into operation, and the primary device availability status of any TYPE_A AC filter of the same type is restored to valid, the selection priority Ax_PRI_2 of AC filter Ax is reset according to the set rules, and it is no longer selected as the next set of filters to be put into operation.

[0078] When the AC filter Ax 1 , AC filter Ax 2...and other priority control enable multiple AC filters, when the same type of AC filter primary device available status is invalid, AC filter Ax 1 , AC filter Ax 2 ...and other multiple AC filter selection priorities are updated synchronously according to the set rules until one is selected as the next set of filters to be put into use. According to the setting difference of priority 2, AC filter Ax 1 , AC filter Ax 2 ...and other AC filters are open for selection in sequence. After the selection is completed, the remaining filter selection priorities maintain the current state, and the opening order corresponding to the priority 2 setting does not change.

[0079] Step 3: Based on the selection priority of each AC filter, generate the logically available state of each AC filter, and implement loop traversal within the set of AC filters of the same type.

[0080] The selection priority of each AC filter is judged by the threshold condition, and the priority selection enable of the corresponding filter is obtained. The available state of the primary equipment of each AC filter and the priority selection enable of the corresponding filter are operated by AND logic, and the operation results are used as the logical available state of the corresponding filter. Based on the logical available state of the AC filter, the filter input selection logic is used to implement loop traversal to achieve the average number of times the same type of AC filters are put into operation.

[0081] Further preferably but not limiting, Figure 3 A schematic diagram of filter input selection logic for loop traversal provided in an embodiment of the present application, wherein:

[0082] The Ax_PRI_EN signal represents the priority selection enable of the AC filter Ax, that is, A1_PRI_EN, A2_PRI_EN...AM_PRI_EN represent the priority selection enable corresponding to the AC filter 1 to the AC filter M respectively, indicating that the AC filter Ax can be opened and its selection priority Ax_PRI_2 represents its opening order, and multiple priority selection enables can be valid at the same time; for example but not limited to, Ax_PRI_EN=1 indicates that the priority selection enable of the AC filter Ax is in a valid state; correspondingly, Ax_PRI_EN=0 indicates that the priority selection enable of the AC filter Ax is in an invalid state.

[0083] The channel number is selected by the TYPE_A_SEL signal and used as the filter input selection logic. For example but not limited to, TYPE_A_SEL=x indicates that the output channel x where the AC filter Ax is located is selected.

[0084] The TYPE_A_AVAIL signal indicates the logically available state corresponding to the selected channel; for example but not limited to, TYPE_A_AVAIL=1 represents that the current output channel is in a logically available state, and TYPE_A_AVAIL=0 represents that the current output channel is in a logically unavailable state.

[0085] Combined with the primary device availability status and selection priority of the AC filter, the logic availability status of each AC filter is generated by calculation, and the filter input selection logic is used to implement loop traversal based on the logic availability status of each AC filter.

[0086] The operation to generate the logical available state Ax_AVAIL_2 of the AC filter Ax specifically includes: the selection priority Ax_PRI_2 of the AC filter Ax is judged by the threshold condition TYPE_A_PRIth, for example but not limited to, whether it is greater than 0; if the threshold condition TYPE_A_PRIth is met, the priority selection enable Ax_PRI_EN of the AC filter Ax = 1, which is a valid state, otherwise Ax_PRI_EN = 0, which is an invalid state; the primary device available state Ax_AVAIL of the AC filter Ax and the priority selection enable Ax_PRI_EN of the AC filter Ax are subjected to an AND logic operation, and the operation result is used as the logical available state Ax_AVAIL_2 of the AC filter Ax.

[0087] Based on the logical available state Ax_AVAIL_2 of the AC filter Ax, the filter input selection logic is used to implement the loop traversal, which specifically includes:

[0088] The traversal function receiving channels 1, 2...M respectively receive the logic available states A1_AVAIL_2, A2_AVAIL_2...AM_AVAIL_2 corresponding to the AC filter 1 to the AC filter M, and the receiving filter input selection logic TYPE_A_SEL value is used to control the selection of the input channel logic available state Ax_AVAIL_2 as the output of the traversal function;

[0089] If the logic available state TYPE_A_AVAIL of the output channel is valid, the filter input selection logic TYPE_A_SEL maintains the currently selected channel;

[0090] If the logical available state TYPE_A_AVAIL of the output channel is invalid, the filter input selection logic TYPE_A_SEL selects the next channel and detects its logical available state by accumulating the counter;

[0091] If the filter input selection logic TYPE_A_SEL selects output channel M and the logic available state TYPE_A_AVAIL of output channel M is invalid, the counter state is reset, and the filter input selection logic TYPE_A_SEL selects the output channel updated to output channel 1 to implement loop traversal.

[0092] Step 4: Based on the selected channel number and the available status of the primary device, the corresponding filter input selection state is enabled, and this state is used to select the input filter.

[0093] If the AC filters in the set type of AC filter set simultaneously meet the conditions that the AC filter is the selected channel number, the filter type is allowed to be put into use, and the primary device availability status is valid, the AC filter becomes the AC filter selected for use among the same type of AC filters.

[0094] Further preferably but not limiting, Figure 4 This is a filter selection logic diagram of an embodiment of the present application, wherein:

[0095] The NEXT_TYPE_A signal indicates that a TYPE_A filter is allowed to be put into operation. For example, but not limited to, NEXT_TYPE_A=1 indicates that a TYPE_A filter is allowed to be put into operation, and NEXT_TYPE_A=0 indicates that a TYPE_A filter is not allowed to be put into operation. The same is true for other types of filters. For example, but not limited to, the NEXT_TYPE_B signal indicates that a TYPE_B filter is allowed to be put into operation.

[0096] The Ax_NEXT_CONN signal indicates that the AC filter Ax has become a selected input filter in the TYPE_A filter, that is, A1_NEXT_CONN, A2_NEXT_CONN...AM_NEXT_CONN respectively represent that the filters A1 to AM have become a selected input filter in the TYPE_A filter; for example, but not limited to, Ax_NEXT_CONN = 1 indicates that the AC filter Ax has become a selected input filter in the TYPE_A filter, and Ax_NEXT_CONN = 0 indicates that the AC filter Ax is not a selected input filter in the TYPE_A filter. The same is true for other types of filters, for example, but not limited to, the By_NEXT_CONN signal indicates that the AC filter By has become a selected input filter in the TYPE_B filter.

[0097] If the AC filter Ax in the TYPE_A filter satisfies the conditions that the AC filter is the selected channel number, the filter type is allowed to be put into operation, and the primary device available state is valid, the AC filter becomes the AC filter selected for the same type of AC filter. For example but not limited to, for AC filter Ax, if the filter input selection logic TYPE_A_SEL = x, the TYPE_A filter allows the input state NEXT_TYPE_A = 1, and the primary device available state Ax_AVAIL of AC filter Ax = 1, then AC filter Ax becomes the selected input state Ax_NEXT_CONN = 1 in the TYPE_A filter, and AC filter Ax becomes the filter selected for input in the TYPE_A filter.

[0098] It can be understood that if the currently allowed filter type is another type, for example but not limited to, the TYPE_A filter is allowed to be put into operation in the state NEXT_TYPE_A=0, and the TYPE_B filter is allowed to be put into operation in the state NEXT_TYPE_B=1, then the TYPE_A filter is not allowed to be put into operation, and the TYPE_B filter is selected in a similar manner.

[0099] After replacing the available status, priority and other input judgment signals related to the filter input selection logic of the cyclic traversal with the exit judgment signal, the filter exit selection logic of the cyclic traversal is realized.

[0100] Table 1: Signals and corresponding descriptions of the accompanying drawings of the embodiment

[0101] Serial number signal name Description Name 1 Ax_AVAIL A device available status 2 Ax_AVAIL_1 Internal availability status 3 Ax_AVAIL_2 Logical availability status 4 TYPE_A_SEL Select channel number 5 TYPE_A_AVAIL Select the logical available state of the channel 6 Ax_PRI_EN Prioritize enabling 7 Ax_PRI_1 Initial Priority 8 Ax_PRI_2 Select Priority 9 Ax_ENA Priority control enable 10 NEXT_TYPE_A Allows the use of this filter type 11 Ax_NEXT_CONN Filter input selection status

[0102] Embodiment 2 of the present invention provides an AC filter priority input / output selection system, which runs an AC filter priority input / output selection method described in embodiment 1, including: an internal available state signal update logic module, a selection priority update logic module, a loop traversal filter selection logic module and a filter input selection logic module;

[0103] The internal available state signal update logic module generates an initial priority for each AC filter of the same type of AC filters, and further generates an internal available state of the AC filter in a set of AC filters of the same type;

[0104] The priority update logic module is selected to update the internal available state generated by the logic module according to the internal available state signal, and configure the selection priority of the AC filter;

[0105] The filter selection logic module of the loop traversal generates a logically available state of each AC filter based on the selection priority of each AC filter, and uses the filter input / exit selection logic to generate a selection channel sequence number based on the logically available state of each AC filter to realize the loop traversal;

[0106] The filter activation / deactivation selection logic module selects the channel number and the available status of the primary device to select the AC filter to be activated / deactivated.

[0107] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. An AC filter priority input / exit selection method for DC power transmission reactive power control, characterized in that: include: generating an initial priority for each AC filter of the same type of AC filters, and further generating an internal availability state of the AC filter in a set of AC filters of the same type; If there is an AC filter of the same type with a valid internal available state, all initial priorities of the filters of this type are given to the selection priority, otherwise the selection priority of the filters of this type is updated according to the set rules; Based on the selection priority of each AC filter, a logically available state of each AC filter is generated, and based on the logically available state of each AC filter, a filter input / exit selection logic is used to generate a selection channel sequence number to realize a cyclic traversal; The AC filter is selected to be enabled / disabled based on the selected channel number and the available status of the primary device.

2. The AC filter priority input / output selection method according to claim 1, characterized in that: The generating of initial priorities for each AC filter of the same type includes: According to the priority control enable signal state, the initial priority of the AC filter is set to one of priority 1 or priority 2. Priority 1 and priority 2 are two sets. The initial priority of the AC filter is a specific value of priority 1 or priority 2. The value of priority 1 is greater than the threshold value, and the value of priority 2 does not exceed the threshold value.

3. The AC filter priority entry / exit selection method according to claim 2, characterized in that: The further generating of the internal available state of the AC filter in a set of AC filters of the same type comprises: When the priority control enable signal of the AC filter is invalid, the initial priority of the AC filter is set to a priority level 1 higher than the threshold value, and further, if the primary device of the AC filter is available, the internal available state of the AC filter is valid; if the primary device of the AC filter is unavailable, the internal available state of the AC filter is invalid; When the priority control enable signal of the AC filter is effective, the initial priority of the AC filter is set to priority 2 which is lower than the threshold value, and the internal availability state of the AC filter is invalid regardless of whether the primary device of the AC filter is available.

4. The AC filter priority entry / exit selection method according to claim 1, characterized in that: The updating of the selection priority of the filter according to the set rules includes: If the priority control enable of the AC filter is effective, the internal available states of the same type of AC filters are invalid and the current selection priority of the AC filter is not higher than the set threshold, the selection priority of the AC filter is increased; otherwise, the selection priority of the AC filter is maintained.

5. The AC filter priority entry / exit selection method according to claim 4, characterized in that: During the operation and maintenance of the DC system, if a special situation occurs in which an AC filter primary device has an abnormality or hidden danger, it is necessary to limit the use of the device without affecting the power upper limit of the DC system during operation, and enable the priority control of the AC filter separately to make the priority 2 of the AC filter effective; After being put into operation, when the primary device availability status of any AC filter of the same type as the AC filter is valid, the selection priority of the AC filter does not meet the threshold condition, so as to prevent the AC filter from being selected as the next group of filters to be put into operation; When the available status of the primary devices of the same type of AC filter as this AC filter is invalid, the selection priority of this AC filter is updated according to the set rules until the selection priority meets the threshold condition, and this AC filter is selected as the next group of filters to be put into use; When the AC filter is selected as the next set of filters to be put into operation, and the primary device availability status of any AC filter of the same type is restored to be valid, the selection priority of the AC filter is reset according to the set rules, and it is no longer selected as the next set of filters to be put into operation.

6. The AC filter priority entry / exit selection method according to claim 5, characterized in that: When priority control of multiple AC filters is enabled and the primary equipment availability status of the same type of AC filters is invalid, the selection priority of the multiple AC filters enabled by priority control is updated synchronously according to the set rules until one of them is selected as the next group of filters to be put into use; According to the setting difference of priority 2, priority control enables multiple AC filters to be opened and selected in sequence; After the selection is completed, the remaining filter selection priorities maintain their current state and the opening order corresponding to the priority 2 setting does not change.

7. An AC filter priority entry / exit selection method according to claim 1 or 4, characterized in that: The generating of the logically available state of each AC filter based on the selection priority of each AC filter includes: The selection priority of each AC filter is judged by the threshold condition to obtain the priority selection enable of the corresponding filter. The primary device availability status of each AC filter and the priority selection enable of the corresponding filter are subjected to AND logic operation, and the operation results are respectively used as the logical availability status of the corresponding filter.

8. The AC filter priority entry / exit selection method according to claim 7, characterized in that: The method of using the filter input / exit selection logic to generate the selection channel sequence number based on the available state of each AC filter logic to realize the cyclic traversal includes: The filter input / exit selection logic takes all the logically available states of the same type of AC filters as input, and takes the selected channel number and the logically available state corresponding to the selected channel as output; If the logic available state of the selected channel is valid, the filter entry / exit selection logic maintains the currently selected channel; If the logically available state of the selected channel is invalid, the filter input / exit selection logic selects the next channel and detects its logically available state by accumulating the counter; if the filter input / exit selection logic selects the maximum output channel and the logically available state is invalid, the counter state is reset, and the selected channel is updated to channel 1 to achieve loop traversal.

9. The AC filter priority entry / exit selection method according to claim 1, characterized in that: The AC filter selected to be put into operation / exited based on the selected channel sequence number and the available state of the primary device includes: If the channel where the AC filter is located is the channel selected by the filter activation / deactivation selection logic, the AC filter of this type is allowed to be activated / deactivated, and the primary device status of the AC filter is valid, then the AC filter becomes the filter selected for activation / deactivation among the AC filters of the same type.

10. An AC filter priority start / stop selection system, running an AC filter priority start / stop selection method according to any one of claims 1 to 9, characterized in that: include: An internal available status signal update logic module, a selection priority update logic module, a looped filter selection logic module, and a filter input selection logic module; The internal available state signal update logic module generates an initial priority for each AC filter of the same type of AC filters, and further generates an internal available state of the AC filter in a set of AC filters of the same type; The priority update logic module is selected to update the internal available state generated by the logic module according to the internal available state signal, and configure the selection priority of the AC filter; The filter selection logic module of the loop traversal generates a logically available state of each AC filter based on the selection priority of each AC filter, and uses the filter input / exit selection logic to generate a selection channel sequence number based on the logically available state of each AC filter to realize the loop traversal; The filter activation / deactivation selection logic module selects the channel number and the available status of the primary device to select the AC filter to be activated / deactivated.

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