Converter unit input method and device, computer equipment and readable storage medium

Abstract

The invention discloses a converter unit input method and device, computer equipment and a readable storage medium, and belongs to the technical field of direct current transmission. The converter unit input method comprises the following steps: after the direct-current voltage of a direct-current power transmission system is reduced to a direct-current voltage threshold, closing a high-voltage side switch of a to-be-input converter unit; in a preset time range, in response to a closing signal of the high-voltage side switch, unlocking the converter unit to be input, and redistributing the power of all the converter units; or, if the closing signal is not received within the preset time range, isolating the to-be-input converter unit, and disconnecting the AC switch and the high-voltage side switch in the to-be-input converter unit. Therefore, by reducing the voltage of the direct-current power transmission system, closing the high-voltage side switch of the to-be-input converter unit and judging whether the to-be-input converter unit is unlocked or not according to whether the closing signal is received or not, the converter unit is input in the operation process of the direct-current power transmission system, and the safety of the alternating-current and direct-current power transmission system is better protected.

Description

Technical Field

[0001] The present application belongs to the field of direct current transmission technology, and specifically relates to a method and device for putting a converter unit into operation, a computer device and a readable storage medium. Background Art

[0002] The DC transmission system has the advantages of large transmission capacity, high voltage level, low operating loss and long transmission distance, and is suitable for long-distance and large-capacity power transmission. At present, the DC transmission system is mainly a two-terminal system, including a transmission line, a sending end and a receiving end connected by a transmission line. Specifically, the rectifier station at the sending end is connected to an AC system. The rectifier station converts AC power into DC power and injects it into the transmission line. The inverter station at the receiving end receives the DC power in the transmission line and converts it into AC power for users, thereby realizing power transmission between the two areas.

[0003] In order to achieve greater capacity of power transmission or flexibility in resource allocation between multiple regions, the scheme of using multiple converters in parallel in rectifier stations or inverter stations is gradually being adopted. The scheme of multiple converters in parallel requires a single converter to be put into operation. However, the input of the converter needs to be achieved by shutting down the DC transmission system or by phase shifting the DC transmission system. Both of the above methods will interrupt the power operation of the DC transmission system and affect the safety of the AC system connected to the DC transmission system. Summary of the invention

[0004] Purpose of the invention: The present application provides a method for putting a converter unit into operation, which is used to put a converter unit into operation during the operation of a DC transmission system; another purpose of the present application is to provide a converter unit putting into operation device; another purpose of the present application is to provide a computer device for implementing the above-mentioned control method; another purpose of the present invention is to provide a computer-readable storage medium for storing a computer program for implementing the above-mentioned control method.

[0005] Technical solution: A converter unit input method of the present application is used to input a converter unit into a DC transmission system, wherein the DC transmission system includes a rectifier station and an inverter station, wherein a plurality of the converter units are arranged in parallel in the rectifier station and / or the inverter station, wherein the converter unit includes a current source converter, a converter transformer and an AC switch connected in sequence to the AC side of the current source converter, and a high-voltage side switch connected in series to the DC side of the current source converter;

[0006] The converter unit input method comprises the following steps:

[0007] After the DC voltage of the DC power transmission system is reduced to a DC voltage threshold, the high-voltage side switch of the converter unit to be put into operation is closed; the DC voltage threshold is a DC voltage value that the DC power transmission system allows the converter unit to be put into operation;

[0008] Within a preset time range, in response to the closing signal of the high-voltage side switch, the converter unit to be put into operation is unlocked and the power of all the converter units is redistributed; or, if the closing signal is not received within the preset time range, the converter unit to be put into operation is isolated, and the AC switch and the high-voltage side switch in the converter unit to be put into operation are disconnected.

[0009] In some embodiments, the DC voltage threshold has a value range of 0 to 0.8 pu, where pu is the rated DC voltage.

[0010] In some embodiments, it also includes:

[0011] In response to a converter unit startup command, the DC voltage of the DC power transmission system is reduced to the DC voltage threshold, and the high-voltage side switch of the converter unit to be put into operation is closed; wherein the converter unit that controls the DC voltage of the DC power transmission system is a master converter unit, and after receiving the converter unit startup command, the master converter unit executes to reduce the DC voltage of the DC power transmission system to the DC voltage threshold;

[0012] Alternatively, after the DC voltage drops to the DC voltage threshold, the converter unit start-up command is accepted, and the high-voltage side switch of the converter unit to be started is closed.

[0013] In some embodiments, reducing the DC voltage of the DC power transmission system to a DC voltage threshold comprises the following steps:

[0014] reducing a DC voltage reference value of the current source converter in the master control converter unit to a first threshold value;

[0015] Alternatively, the operating angle of the current source converter in the master converter unit is increased to a second threshold.

[0016] In some embodiments, when the DC voltage is reduced, adjusting the tap changer of the converter transformer is prohibited.

[0017] In some embodiments, the first threshold value ranges from 0 to 0.8 pu, where pu is the rated DC voltage.

[0018] In some embodiments, increasing the operating angle of the current source converter in the master converter unit to a second threshold value includes:

[0019] The operating angle is increased to the second threshold at a first rate; the first rate ranges from 0.1 to 100° / ms, and the second threshold ranges from 30° to 90°; the operating angle is a trigger angle when the current source converter operates in a rectification mode, or a shutdown angle when the current source converter operates in an inverter mode.

[0020] In some embodiments, in response to receiving a converter unit commissioning command, the DC voltage of the DC transmission system is reduced to the DC voltage threshold, and the converter unit commissioning method further includes: after unlocking the converter unit to be commissioned or isolating the converter unit to be commissioned, automatically restoring the DC voltage to an initial state.

[0021] In some embodiments, the DC voltage is automatically restored at a second rate, and the second rate ranges from 0.1 to 100° / ms.

[0022] In some embodiments, after the DC voltage is reduced to the DC voltage threshold, when the converter unit startup command is accepted, the converter unit startup method further includes: after unlocking the converter unit to be started or isolating the converter unit to be started, maintaining the current state of the DC voltage unchanged.

[0023] In some embodiments, the preset time range is in the range of 50 to 2000 ms.

[0024] In some embodiments, the converter unit startup method further includes:

[0025] According to the preset converter unit input mode, a single converter unit is put into operation, or multiple converter units are put into operation at the same time.

[0026] In some embodiments, when a plurality of the inverter units are put into operation at the same time, if some of the inverter units are not unlocked, only the inverter units that are not unlocked are isolated.

[0027] Correspondingly, the present application also provides a converter unit startup device, which is used to execute the converter unit startup method of the DC power transmission system as described in any one of the above embodiments;

[0028] The converter unit input device comprises:

[0029] A collection module, used for collecting the DC voltage of the DC power transmission system, the position status of the AC and DC field switch and the input command of the converter unit;

[0030] A determination module, used for determining whether to put the converter unit to be put into operation according to the DC voltage and the converter unit input command;

[0031] A control module, configured to close the high-voltage side switch of the converter unit to be put into operation after the DC voltage of the DC power transmission system is reduced to a DC voltage threshold; the DC voltage threshold is a DC voltage value that the DC power transmission system allows the converter unit to be put into operation;

[0032] Within a preset time range, in response to the closing signal of the high-voltage side switch, the converter unit to be put into operation is unlocked and the power of all the converter units is redistributed; or, if the closing signal is not received within the preset time range, the converter unit to be put into operation is isolated, and the AC switch and the high-voltage side switch in the converter unit to be put into operation are disconnected.

[0033] Correspondingly, the present application also provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the steps of the converter unit input method as described in any one of the above embodiments are implemented.

[0034] Accordingly, the present application also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the converter unit input method as described in any one of the above embodiments.

[0035] Beneficial effect: Compared with the prior art, the present application provides a method for putting a converter unit into operation, which is used to put a converter unit into a DC transmission system. The DC transmission system includes a rectifier station and an inverter station. A plurality of converter units are arranged in parallel in the rectifier station and / or the inverter station. The converter unit includes a current source converter, a converter transformer and an AC switch connected in sequence to the AC side of the current source converter, and a high-voltage side switch connected in series to both ends of the DC side of the current source converter. The method for putting a converter unit into operation includes the following steps: after the DC voltage of the DC transmission system is reduced to a DC voltage threshold, closing the high-voltage side switch of the converter unit to be put into operation; the DC voltage threshold is the DC voltage value that the DC transmission system allows the converter unit to be put into operation; within a preset time range, in response to a closing signal of the high-voltage side switch, unlocking the converter unit to be put into operation, and redistributing the power of all converter units; or, if no closing signal is received within the preset time range, isolating the converter unit to be put into operation, and disconnecting the AC switch and the high-voltage side switch in the converter unit to be put into operation. In this way, the present application reduces the voltage of the DC transmission system, closes the high-voltage side switch of the converter unit to be put into operation, and then determines whether to unlock the converter unit to be put into operation based on whether a closing signal is received, thereby realizing the putting into operation of the converter unit during the operation of the DC transmission system, better protecting the safety of the AC / DC transmission system, and ensuring the safety of the AC system connected to the DC transmission system.

[0036] It can be understood that the converter unit input device provided in the present application has all the technical features and beneficial effects of the above-mentioned converter unit input method, which will not be repeated here.

[0037] It can be understood that the computer device provided in the present application has all the technical features and beneficial effects of the above-mentioned converter unit input method, which will not be described in detail here.

[0038] It can be understood that the computer-readable storage medium provided in the present application has all the technical features and beneficial effects of the above-mentioned converter unit commissioning method, which will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The technical solution and other beneficial effects of the present application will be made apparent by describing in detail the specific implementation methods of the present application in conjunction with the accompanying drawings.

[0040] Figure 1 A schematic diagram of a flow chart of a method for putting a converter unit into operation provided in the present application;

[0041] Figure 2 is a schematic structural diagram of a converter unit;

[0042] Figure 3 It is a schematic diagram of the first structure of the DC transmission system;

[0043] Figure 4 A schematic diagram of a flow chart of a converter unit input device provided in the present application;

[0044] Figure 5 is a second structural schematic diagram of a DC transmission system;

[0045] Figure 6 is a third structural schematic diagram of a DC transmission system;

[0046] Figure 7 is a fourth structural schematic diagram of a DC transmission system;

[0047] Figure 8 is a fifth structural schematic diagram of a DC transmission system;

[0048] Fig. 9 This is the sixth structural schematic diagram of the DC transmission system. DETAILED DESCRIPTION

[0049] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0050] In the description of the present application, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or can communicate with each other; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more features.

[0051] The disclosure below provides many different embodiments or examples to realize the different structures of the present application. In order to simplify the disclosure of the present application, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application.

[0052] The applicant has found that in order to achieve greater capacity of power transmission or flexibility in resource allocation between multiple regions, the scheme of using multiple converters in parallel in rectifier stations or inverter stations has gradually been adopted. The scheme of multiple converters in parallel requires a single converter to be put into operation. However, the input of the converter needs to be achieved by shutting down the DC transmission system or by phase shifting the DC transmission system. Both of the above methods will interrupt the power operation of the DC transmission system and affect the safety of the AC system connected to the DC transmission system.

[0053] An embodiment of the present application provides a method for putting a converter unit into operation to solve the above-mentioned technical problem.

[0054] See also Figure 1 , Figure 2 and Figure 3 , Figure 1 A schematic diagram of a process flow of a method for putting a converter unit into operation provided by the present application is shown. Figure 2 The schematic diagram of the structure of the converter unit is shown. Figure 3The first structural schematic diagram of the DC transmission system is illustrated. The embodiment of the present application provides a method for putting a converter unit into operation, which is used to put a converter unit into the DC transmission system. The DC transmission system includes a rectifier station and an inverter station, and multiple converter units are arranged in parallel in the rectifier station and / or the inverter station. The DC transmission system used in the present application includes at least three converter units, and the rectifier station and the inverter station each include at least one converter unit, that is, the rectifier station has one converter unit and the inverter station has at least two converter units, or the rectifier station has at least two converter units and the inverter station has one converter unit, or the rectifier station has at least two converter units and the inverter station has at least two converter units. The converter unit includes a current source converter C1, a converter transformer T1 and an AC switch K1 connected in series with the AC side of the current source converter C1 in sequence, and a high-voltage side switch K2 or K3 connected in series with both ends of the DC side of the current source converter C1. It should be noted that, according to different operation modes and main connections of the current source converter C1, the switch K2 and the switch K3 can be high-voltage side switches respectively.

[0055] The method for putting the converter unit into operation in the embodiment of the present application includes the following steps: after the DC voltage of the DC transmission system is reduced to the DC voltage threshold, the high-voltage side switch K2 or K3 of the converter unit to be put into operation is closed; wherein the DC voltage threshold is the DC voltage value that the DC transmission system allows the converter unit to be put into operation. Within the preset time range, in response to the closing signal of the high-voltage side switch K2 or K3, the converter unit to be put into operation is unlocked, and the power of all converter units is redistributed; or, if the closing signal is not received within the preset time range, the converter unit to be put into operation is isolated, and the AC switch K1 and the high-voltage side switch K2 or K3 in the converter unit to be put into operation are disconnected. Wherein, the value range of the DC voltage threshold is 0 to 0.8 pu, and pu is the rated DC voltage. The value range of the preset time range is 50 to 2000 ms. In this way, the present application reduces the voltage of the DC power transmission system, closes the high-voltage side switch K2 or K3 of the converter unit to be put into operation, and then, if the closing signal generated by the closing of the high-voltage side switch K2 or K3 is received within the preset time range, the converter unit to be put into operation is unlocked, the converter unit to be put into operation is successfully put into the DC power transmission system, and the power of all the converter units that have been put into operation is redistributed; if the closing signal generated by the closing of the high-voltage side switch K2 or K3 is not received within the preset time range, the converter unit to be put into operation is isolated, and the AC switch K1 and the high-voltage side switch K2 or K3 in the converter unit to be put into operation are disconnected, and the converter unit to be put into operation fails to be put into the DC power transmission system. At this time, the converter unit to be put into operation can be re-put into operation or subsequent operations can be stopped as needed.

[0056] In the embodiment of the present application, the DC voltage reduction also includes two situations: in response to the converter unit start-up command, the DC voltage of the DC transmission system is reduced to the DC voltage threshold, and the high-voltage side switch K2 or K3 of the converter unit to be put into operation is closed; wherein, the converter unit that controls the DC voltage of the DC transmission system is a main control converter unit, and the main control converter unit can be a converter unit in a rectifier station or a converter unit in an inverter station. After receiving the converter unit start-up command, the main control converter unit executes to reduce the DC voltage of the DC transmission system to the DC voltage threshold; or, after the DC voltage is reduced to the DC voltage threshold, the converter unit receives the converter unit start-up command and closes the high-voltage side switch K2 or K3 of the converter unit to be put into operation. That is to say, the starting conditions of the present application are divided into two situations. One is that after the master converter unit receives the converter unit start-up command, the master converter unit controls the DC transmission system to reduce the voltage, and then closes the high-voltage side switch K2 or K3 of the converter unit to be put into operation; the other is that before issuing the converter unit start-up command, the DC transmission system has been completed by the operating personnel. The voltage reduction operation, in this way, does not require the master converter unit to control the DC transmission system to reduce the voltage. After receiving the converter unit start-up command, the high-voltage side switch K2 or K3 of the converter unit to be put into operation can be directly closed.

[0057] In addition, the present application can use two methods to reduce the DC voltage of the DC transmission system to the DC voltage threshold. They are: reducing the DC voltage reference value of the current source converter C1 in the main control converter unit to a first threshold; wherein the value range of the first threshold is 0 to 0.8pu, and pu is the rated DC voltage; or, increasing the operating angle of the current source converter C1 in the main control converter unit to a second threshold. It should be noted that when reducing the DC voltage, it is prohibited to adjust the tap switch of the converter transformer T1, so as to ensure the stability of the DC transmission system when the voltage is reduced.

[0058] Specifically, increasing the operating angle of the current source converter C1 in the main control converter unit to the second threshold includes: increasing the operating angle to the second threshold at a first rate; wherein the first rate has a value range of 0.1 to 100° / ms, and the second threshold has a value range of 30° to 90°; the operating angle is a trigger angle when the current source converter C1 operates in a rectification mode, or a shutdown angle when the current source converter C1 operates in an inverter mode.

[0059] According to the two situations of the starting conditions of the present application, the present application also includes two situations after completing the unlocking of the converter unit to be put into operation or the isolation of the converter unit to be put into operation. The first is that in response to receiving the converter unit input command, the DC voltage of the DC transmission system is reduced to the DC voltage threshold. The converter unit input method also includes: after unlocking the converter unit to be put into operation or isolating the converter unit to be put into operation, the DC voltage is automatically restored to the initial state. Specifically, at this time, the DC voltage is automatically restored at a second rate, and the value range of the second rate is 0.1~100° / ms. The initial state is the state before the converter unit to be put into operation is unlocked and put into operation. The second is that after the DC voltage is reduced to the DC voltage threshold, when the converter unit input command is accepted, the converter unit input method also includes: after unlocking the converter unit to be put into operation or isolating the converter unit to be put into operation, the current state of the DC voltage is kept unchanged.

[0060] Furthermore, a method for putting a converter unit into operation provided by the present application also includes: putting a single converter unit into operation, or putting multiple converter units into operation at the same time, according to a pre-set converter unit operation mode. In other words, through the scheme of the present application, it is possible to put a single converter unit into operation, or put multiple converter units into operation at the same time. When multiple converter units are put into operation at the same time, if some of the converter units are not unlocked, only the unlocked converter units are isolated, and the remaining unlocked converter units can be put into operation normally.

[0061] Furthermore, the present application is applicable to Figure 3 The DC transmission system shown in FIG. 1 is not limited to this type of DC transmission system. Figure 5 A schematic diagram of a second structure of a DC transmission system is shown; Figure 6 A schematic diagram of the third structure of a DC transmission system is shown; Figure 7 A fourth structural diagram of a DC transmission system is shown; Figure 8 A fifth structural diagram of a DC transmission system is shown; Fig. 9 The sixth structural diagram of the illustrated DC transmission system; that is, a three-terminal or four-terminal DC transmission system is also applicable to the method of the present application, that is, the present application is applicable to all DC transmission systems comprising at least three converter units connected in parallel.

[0062] Next, combine Figure 3 To further illustrate a method for putting a converter unit into operation provided by the present application, Figure 3 A first structural schematic diagram of a DC transmission system is shown.

[0063] by Figure 3Taking the DC transmission system shown as an example, the rectifier station I, rectifier station II and inverter station I in the DC transmission system are all composed of current source converter units, the rectifier station I and the rectifier station II are connected by two DC transmission lines, and the rectifier station II and the inverter station I are connected by two DC transmission lines, wherein: the rectifier station I and the rectifier station II are used to convert the three-phase AC power of the sending-end AC power grid into DC power and then transmit it to the inverter station I through the DC transmission line, and the current source converters in the rectifier station I and the rectifier station II are both composed of current source converter C31. The inverter station I is used to convert DC power into three-phase AC power and then transmit it to the receiving AC power grid. The current source converter in the inverter station I is composed of a current source converter C31. The current source converter C31 is connected to the receiving AC power grid S3 through a three-winding converter transformer T31 with a connection mode of Y0 / Y / Δ. An AC circuit breaker K31 is installed on the primary side of the converter transformer T31. The current source converter C31 is controlled by a fixed DC voltage control strategy.

[0064] At the same time, the current source converter C31 adopts a twelve-pulse bridge circuit; each bridge arm is composed of a number of thyristors connected in series, and the current source converter C31 adopts a fixed DC current control strategy. The current source converter C31 is connected to the sending-end AC grid S1 through a three-winding converter transformer T11 with a connection mode of Y0 / Y / Δ, and an AC circuit breaker K11 is installed on the primary side of the converter transformer T11. The current source converter C21 is connected to the sending-end AC grid S2 through a three-winding converter transformer T21 with a connection mode of Y0 / Y / Δ, and an AC circuit breaker K21 is installed on the primary side of the converter transformer T21. The converter transformer T21 can transform the voltage level of the three-phase AC power of the sending-end AC system to adapt to the required DC voltage level. At the same time, the different secondary side connection methods of the converter transformer T21 provide three-phase AC power with a phase difference of 30° for the upper and lower six-pulse converter bridges of the twelve-pulse bridge current source converter C31 to reduce the harmonic current flowing into the power grid.

[0065] Figure 3In the embodiment, the converter unit 1 of the rectifier converter station I includes a current source converter C11, a high voltage side switch K13 and a low voltage side switch K12 connected in series with the DC side of the current source converter C11, the current source converter C11 is connected to the AC power grid S1 through a converter transformer T11 and an AC switch K11, and the current source converter C11 is in a constant DC current control mode. The converter unit 2 of the rectifier converter station II includes a current source converter C21, a high voltage side switch K23 and a low voltage side switch K22 connected in series with the DC side of the current source converter C21, the current source converter C21 is connected to the AC power grid S2 through a converter transformer T21 and an AC switch K21, and the current source converter C21 is in a constant DC current control mode. The converter unit 3 of the inverter station I includes a current source converter C31, a high voltage side switch K33 and a low voltage side switch K32 connected in series to the DC side of the current source converter C31, the current source converter C31 is connected to the AC power grid S3 through a converter transformer T31 and an AC switch K31, and the current source converter C31 is in a constant DC voltage control mode.

[0066] If the rectifier converter station I and the inverter converter station I are in operation, they are operating at rated DC voltage and rated DC power, that is, Figure 3 The medium current source converter C11 and converter transformer T11 are energized, the AC switch K11 is in the closed position, the high voltage side switch K13 and the low voltage side switch K12 connected in series with the DC side of the current source converter C11 are both in the closed position, and the current source converter C11 is in a constant DC current control mode; the current source converter C31 and converter transformer T31 are energized, the AC switch K31 is in the closed position, the high voltage side switch K33 and the low voltage side switch K32 connected in series with the DC side of the current source converter C31 are both in the closed position, and the current source converter C31 is in a constant DC voltage control mode. At this time, the converter unit 2 in the rectifier converter station II has been overhauled and needs to be put into the running DC system, which can be achieved through the following operations:

[0067] The DC voltage reference value of the current source converter C31 which is in the DC voltage control mode and controls the DC voltage of the DC transmission system is reduced, that is, the DC voltage reference value of the current source converter C31 which controls the DC voltage of the DC transmission system is reduced from the current operating value to 0-0.8pu, where 1pu is the rated DC voltage, for example, the DC voltage reference value of the current source converter C31 is reduced from the current operating value to 0.6pu.

[0068] While lowering the DC voltage reference value of the current source converter C31 that controls the DC voltage of the DC power transmission system, it is allowed to adjust the tap switch (not shown in the figure) of the converter transformer T31 connected to the current source converter C31 to cooperate in lowering the DC voltage of the DC power transmission system.

[0069] When the DC voltage of the operating DC transmission system drops to a range that allows the current source converter C21 to be put into operation, that is, the DC voltage of the operating DC transmission system drops below the DC voltage threshold Uth, the DC voltage threshold Uth ranges from 0 to 0.8pu, where 1pu is the rated DC voltage, for example, Uth is 0.65pu.

[0070] The operator selects and sets the converter input mode on the operating system, and selects a single current source converter for input.

[0071] Operate the converter unit 2 to be put into operation in the rectifier converter station II, connect the AC switch K21, connect the current source converter C21 and the converter transformer T21 to the AC grid S2, the current source converter C21 and the converter transformer T21 are both energized, connect the low-voltage side switch K22 connected in series on the DC side of the current source converter C21, and complete the connection of all switches on the AC and DC sides except the high-voltage side switch K23. At this time, the high-voltage side switch K23 connected in series with the DC side of the current source converter C21 is in the open position.

[0072] After receiving the converter unit start-up command issued by the operator, the high-voltage side switch K23 connected in series on the DC side of the current source converter C21 to be started is closed.

[0073] If the closing signal of the high-voltage side switch K23 is received within the preset time range, the current source converter C21 is unlocked, that is, the current source converter C21 is successfully put into operation, and the power of each current source converter C11, current source converter C21 and current source converter C31 is redistributed. If the closing signal of the high-voltage side switch K23 is not received within the preset time range, the current source converter C21 is isolated, the AC switch K21 is separated, the low-voltage side switch K22 connected in series with the DC side of the current source converter C21 is separated, the high-voltage side switch K23 connected in series with the DC side of the current source converter C21 is separated, and all the switch knives on the AC and DC sides of the current source converter C21 are separated, that is, the current source converter C21 fails to be put into operation. The value range of the preset time range is 50 to 2000ms, for example, 200ms.

[0074] After the current source converter C21 is successfully or unsuccessfully put into operation, the DC voltage of the DC system is not automatically increased from the current operating 0.6pu to the rated DC voltage, and the operation of the operator is waited for to decide whether to restore the DC voltage of the DC system to the rated DC voltage. At this point, the current source converter C21 is put into operation.

[0075] If the rectifier converter station II and the inverter converter station I are in operation, they are operating at rated DC voltage and rated DC power, that is, Figure 3The current source converter C21 and the converter transformer T21 are energized, the AC switch K21 is in the closed position, the high-voltage side switch K23 and the low-voltage side switch K22 connected in series with the DC side of the current source converter C21 are both in the closed position, and the current source converter C21 is in a constant DC current control mode; the current source converter C31 and the converter transformer T31 are energized, the AC switch K31 is in the closed position, the high-voltage side switch K33 and the low-voltage side switch K32 connected in series with the DC side of the current source converter C31 are both in the closed position, and the current source converter C31 is in a constant DC voltage control mode. At this time, the converter unit 1 in the rectifier converter station I has been overhauled and needs to be put into the running DC system, which can be achieved through the following operations:

[0076] The operator selects and sets the inverter unit startup mode on the operating system, and selects a single inverter unit for startup.

[0077] Operate the converter unit 1 to be put into operation in the rectifier converter station I, connect the AC switch K11, the current source converter C11 and the converter transformer T11 are connected to the AC power grid S1, the current source converter C11 and the converter transformer T11 are energized, connect the low-voltage side switch K12 connected in series on the DC side of the current source converter C11, and complete the connection of all switch knives on the AC and DC sides except the high-voltage side switch K13. At this time, the high-voltage side switch K13 connected in series with the DC side of the current source converter C11 is in the open position.

[0078] After receiving the converter start-up command, the operating angle of the current source converter C31 that controls the DC voltage of the DC transmission system is increased, that is, the turn-off angle of the current source converter C31 that controls the DC voltage of the DC transmission system is increased from the current operating value of 17° to 30°~90° at a first rate, wherein the first rate ranges from 0.1 to 100° / ms. For example, the turn-off angle of the current source converter C31 is controlled to increase from the current operating value of 17° to 60° at a rate of 2° / ms. At this time, the DC voltage of the DC transmission system will drop to below 0.6pu.

[0079] While increasing the cut-off angle of the current source converter C31 that controls the DC voltage of the DC power transmission system, it is prohibited to adjust the tap switch (not shown in the figure) of the converter transformer T31 connected to the current source converter C31, so as to reduce the DC voltage of the DC power transmission system.

[0080] When the DC voltage of the operating DC transmission system drops to a range that allows the current source converter C11 to be put into operation, that is, the DC voltage of the operating DC transmission system drops below the DC voltage threshold Uth, and the DC voltage threshold Uth ranges from 0 to 0.8pu, where 1pu is the rated DC voltage, for example, Uth is 0.65pu.

[0081] Close the high-voltage side switch K13 connected in series with the current source converter C11 to be put into operation.

[0082] If the closing signal of the high-voltage side switch K13 is received within the preset time range, the current source converter C11 is unlocked, that is, the current source converter C11 is successfully put into operation, and the power of each current source converter C11, current source converter C21 and current source converter C31 is redistributed. If the closing signal of the high-voltage side switch K13 is not received within the preset time range, the current source converter C11 is isolated, the AC switch K11 is separated, the low-voltage side switch K12 connected in series with the DC side of the current source converter C11 is separated, the high-voltage side switch K13 connected in series with the DC side of the current source converter C11 is separated, and all the switch knives on the AC and DC sides of the current source converter C11 are separated, that is, the current source converter C11 fails to be put into operation. The value range of the preset time range is 50 to 2000ms, for example, 200ms.

[0083] After the current source converter C11 is successfully put into operation or fails to be put into operation, the DC voltage of the DC system is automatically restored to the state before the current source converter C11 is put into operation, that is, after the current source converter C11 is successfully put into operation or fails to be put into operation, the DC voltage of the DC power transmission system is automatically restored at a second rate, wherein the value range of the second rate is 0.1 to 100° / ms, for example, S2 takes a value of 1.5° / ms.

[0084] Compared with the prior art, the present application provides a method for putting a converter unit into operation, which is used to put a converter unit into a DC transmission system. By lowering the voltage of the DC transmission system, the high-voltage side switch of the converter unit to be put into operation is closed, and then whether to unlock the converter unit to be put into operation is determined based on whether a closing signal is received. The converter unit is put into operation during the operation of the DC transmission system, thereby better protecting the safety of the AC / DC transmission system and ensuring the safety of the AC system connected to the DC transmission system.

[0085] Accordingly, an embodiment of the present application further provides a converter unit startup device, which is used to execute a converter unit startup method of a DC power transmission system as described in any one of the above embodiments;

[0086] See also Figure 4 , Figure 4 The flowchart of a converter unit input device provided by the present application is shown; the converter unit input device comprises:

[0087] The acquisition module is used to collect the DC voltage of the DC transmission system, the position status of the AC and DC field switch and the input command of the converter unit;

[0088] A determination module, used for determining whether to put the converter unit to be put into operation according to the DC voltage and the converter unit input command;

[0089] A control module, used for closing the high-voltage side switch of the converter unit to be put into operation after the DC voltage of the DC power transmission system is reduced to a DC voltage threshold; the DC voltage threshold is a DC voltage value that the DC power transmission system allows the converter unit to be put into operation;

[0090] Within the preset time range, in response to the closing signal of the high-voltage side switch, the converter unit to be put into operation is unlocked and the power of all converter units is redistributed; or, if the closing signal is not received within the preset time range, the converter unit to be put into operation is isolated, and the AC switch and high-voltage side switch in the converter unit to be put into operation are disconnected.

[0091] It can be understood that the converter unit input device provided in the present application has all the technical features and beneficial effects of the above-mentioned converter unit input method, which will not be repeated here.

[0092] Correspondingly, an embodiment of the present application further provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the steps of the converter unit input method of any one of the above embodiments are implemented.

[0093] It can be understood that the computer device provided in the present application has all the technical features and beneficial effects of the above-mentioned converter unit input method, which will not be described in detail here.

[0094] Correspondingly, an embodiment of the present application further provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the converter unit input method of any one of the above embodiments.

[0095] It can be understood that the computer-readable storage medium provided in the present application has all the technical features and beneficial effects of the above-mentioned converter unit commissioning method, which will not be described in detail here.

[0096] The above is a detailed introduction to the converter unit input method, device, computer equipment and readable storage medium provided in the embodiments of the present application. Specific examples are used in the present application to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the technical solutions and core ideas of the present application. Ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some of the technical features therein with equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for putting a converter unit into operation, characterized in that: Used to put a converter unit into a direct current transmission system, the direct current transmission system includes a rectifier station and an inverter station, a plurality of the converter units are arranged in parallel in the rectifier station and / or the inverter station, and the converter unit includes a current source converter, a converter transformer and an AC switch connected in sequence to the AC side of the current source converter, and a high-voltage side switch connected in series to the DC side of the current source converter; The converter unit input method comprises the following steps: After the DC voltage of the DC power transmission system is reduced to a DC voltage threshold, the high-voltage side switch of the converter unit to be put into operation is closed; the DC voltage threshold is a DC voltage value that the DC power transmission system allows the converter unit to be put into operation; Within a preset time range, in response to the closing signal of the high-voltage side switch, the converter unit to be put into operation is unlocked and the power of all the converter units is redistributed; or, if the closing signal is not received within the preset time range, the converter unit to be put into operation is isolated, and the AC switch and the high-voltage side switch in the converter unit to be put into operation are disconnected.

2. The method for putting the converter unit into operation according to claim 1, characterized in that: The DC voltage threshold has a value range of 0 to 0.8 pu, where pu is the rated DC voltage.

3. The method for putting a converter unit into operation according to claim 1, characterized in that: Also includes: In response to a converter unit startup command, the DC voltage of the DC power transmission system is reduced to the DC voltage threshold, and the high-voltage side switch of the converter unit to be put into operation is closed; wherein the converter unit that controls the DC voltage of the DC power transmission system is a master converter unit, and after receiving the converter unit startup command, the master converter unit executes to reduce the DC voltage of the DC power transmission system to the DC voltage threshold; Alternatively, after the DC voltage drops to the DC voltage threshold, the converter unit start-up command is accepted, and the high-voltage side switch of the converter unit to be started is closed.

4. The method for putting the converter unit into operation according to claim 3, characterized in that: Reducing the DC voltage of the DC power transmission system to a DC voltage threshold comprises the following steps: reducing a DC voltage reference value of the current source converter in the master control converter unit to a first threshold value; Alternatively, the operating angle of the current source converter in the master converter unit is increased to a second threshold.

5. The method for putting the converter unit into operation according to claim 4, characterized in that: When the DC voltage is reduced, adjusting the tap changer of the converter transformer is prohibited.

6. The method for putting a converter unit into operation according to claim 4, characterized in that: The value range of the first threshold is 0-0.8pu, where pu is the rated DC voltage.

7. The method for putting a converter unit into operation according to claim 4, characterized in that: Increasing the operating angle of the current source converter in the master control converter unit to a second threshold value includes: The operating angle is increased to the second threshold at a first rate; the first rate ranges from 0.1 to 100° / ms, and the second threshold ranges from 30° to 90°; the operating angle is a trigger angle when the current source converter operates in a rectification mode, or a shutdown angle when the current source converter operates in an inverter mode.

8. The method for putting a converter unit into operation according to claim 3, characterized in that: In response to receiving a converter unit startup command, the DC voltage of the DC power transmission system is reduced to the DC voltage threshold, and the converter unit startup method further includes: automatically restoring the DC voltage to an initial state after unlocking the converter unit to be started or isolating the converter unit to be started.

9. The method for putting the converter unit into operation according to claim 8, characterized in that: The DC voltage is automatically restored at a second rate, and the second rate has a value range of 0.1 to 100° / ms.

10. The method for putting a converter unit into operation according to claim 3, characterized in that: After the DC voltage drops to the DC voltage threshold, when the converter unit startup command is accepted, the converter unit startup method further includes: after unlocking the converter unit to be started or isolating the converter unit to be started, keeping the current state of the DC voltage unchanged.

11. The method for putting a converter unit into operation according to claim 1, characterized in that: The preset time range is 50 to 2000 ms.

12. The method for putting a converter unit into operation according to claim 1, characterized in that: The converter unit input method further includes: According to the preset converter unit input mode, a single converter unit is put into operation, or multiple converter units are put into operation at the same time.

13. The method for putting a converter unit into operation according to claim 12, characterized in that: When a plurality of the inverter units are put into operation at the same time, if some of the inverter units are not unlocked, only the inverter units that are not unlocked are isolated.

14. A converter unit input device, characterized in that: Used to execute the converter unit input method of the direct current transmission system as claimed in any one of claims 1 to 13; The converter unit input device comprises: A collection module, used for collecting the DC voltage of the DC power transmission system, the position status of the AC and DC field switch and the input command of the converter unit; A determination module, used for determining whether to put the converter unit to be put into operation according to the DC voltage and the converter unit input command; A control module, configured to close the high-voltage side switch of the converter unit to be put into operation after the DC voltage of the DC power transmission system is reduced to a DC voltage threshold; the DC voltage threshold is a DC voltage value that the DC power transmission system allows the converter unit to be put into operation; Within a preset time range, in response to the closing signal of the high-voltage side switch, the converter unit to be put into operation is unlocked and the power of all the converter units is redistributed; or, if the closing signal is not received within the preset time range, the converter unit to be put into operation is isolated, and the AC switch and the high-voltage side switch in the converter unit to be put into operation are disconnected.

15. A computer device, characterized in that: The method comprises a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the converter unit input method according to any one of claims 1 to 13 when executing the computer program.

16. A computer-readable storage medium, characterized in that: A computer program is stored, and when the computer program is executed by a processor, the steps of the converter unit starting method according to any one of claims 1 to 13 are implemented.

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