Current zero-crossing turn-off method for direct-current transmission converter valve

Abstract

The invention provides a current zero-crossing turn-off method for a direct-current transmission converter valve, which is suitable for the technical field of power electronics, and can solve the problems of zero-crossing turn-off failure and commutation failure of reverse-blocking IGCTs (integrated gate commutation transformers) caused by zero-crossing inconsistency of the reverse-blocking IGCTs in the same rectification circuit, thereby improving the reliability. According to the scheme, N zero-cross detection signals are received, the N zero-cross detection signals come from N reverse blocking type switching devices in the same rectification circuit, and N is a positive integer and is Ngt; 2; and meanwhile, zero-crossing turn-off signals are sent to the N reverse-blocking switching devices, wherein the zero-crossing turn-off signals are used for controlling the N reverse-blocking switching devices to be turned off.

Description

Technical Field

[0001] The invention belongs to the technical field of power electronics, and in particular relates to a method for shutting down a DC power transmission converter valve by zero current crossing. Background Art

[0002] At present, the line-commutated converter (LCC) usually adopts the following Figure 1 The thyristor (Silicon Controlled Rectifier, SCR) shown in the figure is used to achieve this. Figure 2 As shown, when a fault occurs in the power system, the voltage or current may cross zero in advance. Since the reverse recovery time of the thyristor is too long, the thyristor may not have time to complete reverse recovery, and thus reopen in the current direction before zero crossing, resulting in commutation failure.

[0003] To this end, a hybrid multilevel converter (Hybrid Commutated Converter, HCC) is introduced, such as Figure 3 As shown in the figure, the basic principle is to use a high-power reverse blocking (RB) integrated gate commutated thyristor (RB-IGCT) to replace the thyristor in the LCC converter. Since the reverse blocking IGCT contains a drive circuit, the reverse recovery time is very short, and the reverse recovery of the bridge arm current can be quickly completed when the voltage or current passes through zero, so as to solve the problem of commutation failure under minor faults.

[0004] However, since the HCC converter based on the reverse-resistance IGCT has more functions, the control logic based on the LCC converter valve is too simple and cannot match all the requirements of the HCC converter valve, resulting in poor consistency in controlling the zero-crossing of each reverse-resistance IGCT in the HCC converter. There is still a risk of commutation failure caused by the failure of some reverse-resistance IGCTs to shut down at zero crossing, and the reliability is still poor. Summary of the invention

[0005] The present invention proposes a method for shutting down a DC power transmission converter valve current at zero crossing, which can solve the problems of zero crossing shutdown failure and commutation failure caused by poor zero crossing consistency of each reverse resistance IGCT in an HCC converter, thereby improving reliability.

[0006] In view of the above problems, the present invention adopts the following technical solutions:

[0007] In a first aspect, a method for shutting down a DC power transmission converter valve current at zero crossing is provided. The method comprises: receiving N zero crossing detection signals, the N zero crossing detection signals coming from N reverse resistance type switching devices in the same rectifier circuit, N being a positive integer, and N>2; and simultaneously sending a zero crossing shutdown signal to the N reverse resistance type switching devices, the zero crossing shutdown signal being used to control the N reverse resistance type switching devices to shut down.

[0008] The nth zero-crossing detection signal is used to indicate that a current zero-crossing phenomenon or a voltage zero-crossing phenomenon has occurred in the nth reverse resistance switching device, n is a positive integer, and 1≤n≤N.

[0009] Optionally, the zero-crossing detection signal may be a level signal or a coding signal.

[0010] Optionally, the N reverse resistance type switching devices include a driving circuit. Accordingly, the above-mentioned receiving the N zero-crossing detection signals may include: receiving the zero-crossing detection signal from the driving circuit in the N reverse resistance type switching devices.

[0011] Exemplarily, the reverse-resistance switching device may include a reverse-resistance integrated gate-commutated thyristor IGCT, or other reverse-resistance fully-controlled switching devices.

[0012] Based on the current zero-crossing shutdown method for a DC transmission converter valve provided by the present invention, after receiving the zero-crossing detection signals sent by N reverse-resistance type switching devices in the same rectifier circuit, a zero-crossing shutdown signal can be simultaneously sent to the above-mentioned N reverse-resistance type switching devices to ensure that each of the N reverse-resistance type switching devices can be basically shut down at the same time, thereby solving the problem of reverse-resistance type IGCT zero-crossing shutdown failure and commutation failure caused by inconsistent zero-crossing of each reverse-resistance IGCT in the same rectifier circuit, thereby improving reliability.

[0013] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0015] Figure 1 It is a structural schematic diagram of a rectifier circuit based on LCC;

[0016] Figure 2 A schematic diagram of a zero-crossing shutdown failure scenario in an LCC-based rectifier circuit;

[0017] Figure 3 It is a structural schematic diagram of a rectifier circuit based on HCC;

[0018] Figure 4 A schematic diagram of a scenario in which zero-crossing shutdown is successful in a rectifier circuit based on HCC;

[0019] Figure 5 A schematic diagram of the structure of a rectifier circuit provided in an embodiment of the present invention;

[0020] Figure 6 A schematic flow chart of a method for shutting down a DC power transmission converter valve when current passes through zero-crossing is provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] First, receive the rectifier circuit provided by the embodiment of the present invention. Figure 5 As shown, the rectifier circuit includes a commutation control circuit and a commutation circuit. The commutation circuit may include N reverse resistance switch devices in the rectifier circuit for constructing each rectifier bridge arm in the rectifier circuit, and each reverse resistance switch device may include a switch device and a drive circuit. The drive circuit of each reverse resistance switch device can detect whether the voltage or current of the corresponding switch device is zero-crossing by itself. If a zero-crossing event occurs, a zero-crossing detection signal is sent to the commutation control circuit, and then a zero-crossing shutdown signal is received from the commutation control circuit, and the switch device is controlled to complete the zero-crossing shutdown.

[0023] For example, if the driving circuit n in the nth reverse resistance type switching device detects that the corresponding switching device n has a zero crossing event, it can send a zero crossing detection signal n to the commutation control circuit, then receive a zero crossing shutdown signal n from the commutation control circuit, and control the switching device n to complete the zero crossing shutdown operation. Where n and N are positive integers, and 1≤n≤N, N>2.

[0024] For example, please combine Figure 3 The reverse resistance type switching device may include a parallel structure consisting of a reverse resistance type IGCT and a driving circuit, such as an IGCT 2 +DRV 2 IGCT5 +DRV 5 , or other reverse resistance fully controlled switching devices, the commutation control circuit may include valve-based electronic equipment (VBE), or other circuits that can be used to control the commutation circuit to complete zero-crossing shutdown.

[0025] It should be noted that the number of reverse resistance switching devices included may be different depending on the type of rectifier circuit. Figure 5 The commutation circuit in can be Figure 3 The three-phase AC rectifier circuit shown, in this case N=6, can also be a single-phase bridge rectifier circuit, in this case N=4, which is not limited in the embodiment of the present invention.

[0026] The embodiment of the present invention also provides a method for shutting down a DC power transmission converter valve when current passes through zero, which can be applied to Figure 3 In the rectifier circuit shown.

[0027] like Figure 6 As shown, the method comprises the following steps:

[0028] S601, the commutation control circuit receives N zero-crossing detection signals.

[0029] Please combine Figure 5 , N zero-crossing detection signals all come from N reverse-resistance switching devices in the same rectifier circuit, and the nth zero-crossing detection signal is used to indicate that a current zero-crossing event or a voltage zero-crossing event has occurred in the nth reverse-resistance switching device, n and N are positive integers, and 1≤n≤N, N>2.

[0030] Optionally, the zero-crossing detection signal can be a level signal or a coding signal. Wherein, the level signal can be a high level or a low level, and the coding signal can be a binary coded signal. For example, if the high level indicates that a zero-crossing event has occurred, the low level indicates that no zero-crossing event has occurred, or conversely, if the low level indicates that a zero-crossing event has occurred, the high level indicates that no zero-crossing event has occurred. Similarly, if the binary digit 1 indicates that a zero-crossing event has occurred, the binary digit 0 indicates that no zero-crossing event has occurred, or, conversely, if the binary digit 0 indicates that a zero-crossing event has occurred, the binary digit 1 indicates that no zero-crossing event has occurred. The embodiments of the present invention are not limited.

[0031] Optionally, the N reverse resistance type switching devices include a driving circuit. Accordingly, the above-mentioned receiving N zero-crossing detection signals may include the following steps: receiving the zero-crossing detection signal from the driving circuit in the N reverse resistance type switching devices, such as Figure 5 The zero-crossing detection signal 1 to the zero-crossing detection signal N in.

[0032] Exemplarily, the reverse-blocking switching device may include a reverse-blocking integrated gate-commutated thyristor IGCT, or other reverse-blocking fully-controlled switching devices, which is not limited in the embodiments of the present invention.

[0033] S602, the commutation control circuit sends a zero-crossing shutdown signal to N reverse resistance switching devices simultaneously.

[0034] The zero-crossing shutdown signal is used to control the N reverse resistance switching devices to shut down.

[0035] Specifically, please refer to Figure 5 , the commutation control circuit simultaneously sends a zero-crossing shutdown signal to the driving circuits in the N reverse-resistance switching devices, and each driving circuit controls the corresponding reverse-resistance switching device to shut down according to the received zero-crossing shutdown signal. For example, after receiving the zero-crossing shutdown signal n, the driving circuit n in the reverse-resistance switching device n generates a shutdown control signal according to the zero-crossing shutdown signal n and sends it to the control end of the reverse-resistance switching device n, thereby realizing the shutdown operation of the reverse-resistance switching device n, 1≤n≤N.

[0036] It should be noted that the term "simultaneously" can be understood as: the deviation between the zero-crossing shutdown signal 1 sent by the commutation control circuit to the first reverse-resistance switching device and the zero-crossing shutdown signal N sent by the commutation control circuit to the Nth reverse-resistance switching device is less than or equal to a certain time deviation threshold, which is usually small, such as 50 nanoseconds, 60 nanoseconds, 80 nanoseconds, etc. In this way, the time when each zero-crossing shutdown signal arrives at each reverse-resistance switching device is basically the same, so that each reverse-resistance switching device can complete the shutdown operation "synchronously" or "approximately synchronously" to improve the consistency of the zero-crossing shutdown operation of each reverse-resistance switching device, thereby reducing the risk of commutation failure and improving reliability.

[0037] For example, the commutation control circuit can trigger the action of sending a zero-crossing shutdown signal to all reverse-resistance switching devices at the same time after receiving the zero-crossing detection signal sent by all reverse-resistance switching devices in the same rectifier circuit. Among them, the control signal used to indicate "the same time" can be generated based on the clock signal of the commutation control circuit, so as to achieve accurate control of the sending time of the zero-crossing shutdown signal. Alternatively, the different connection delays between different reverse-resistance switching devices and the commutation control circuit can also be considered to fine-tune the sending time of the zero-crossing shutdown signal sent to different reverse-resistance switching devices to ensure that the time when each zero-crossing shutdown signal arrives at each reverse-resistance switching device is the same.

[0038] Based on the current zero-crossing shutdown method for a DC transmission converter valve provided in an embodiment of the present invention, after receiving zero-crossing detection signals sent by N reverse-resistance switching devices in the same rectifier circuit, a zero-crossing shutdown signal can be simultaneously sent to the above-mentioned N reverse-resistance switching devices to ensure that each of the N reverse-resistance switching devices can be basically shut down at the same time, thereby solving the problem of reverse-resistance IGCT zero-crossing shutdown failure and commutation failure caused by inconsistent zero-crossing of each reverse-resistance IGCT in the same rectifier circuit, thereby improving reliability.

[0039] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for shutting down a DC power transmission converter valve when current passes through zero, characterized in that: include: Receiving N zero-crossing detection signals, where the N zero-crossing detection signals come from N reverse resistance switching devices in the same rectifier circuit, where N is a positive integer and N>2; At the same time, a zero-crossing shutdown signal is sent to the N reverse-resistance switching devices, and the zero-crossing shutdown signal is used to control the N reverse-resistance switching devices to shut down.

2. The method for shutting down a DC power transmission converter valve when current passes through zero-crossing according to claim 1, characterized in that: The nth zero-crossing detection signal is used to indicate that a current zero-crossing phenomenon or a voltage zero-crossing phenomenon has occurred in the nth reverse resistance type switching device, where n is a positive integer and 1≤n≤N.

3. The method for shutting down a DC power transmission converter valve when current passes through zero-crossing according to claim 1, characterized in that: The zero-crossing detection signal is a level signal or a coding signal.

4. The method for shutting down a DC power transmission converter valve when current passes through zero-crossing according to claim 1, characterized in that: The N reverse resistance switching devices include a driving circuit; The receiving N zero-crossing detection signals comprises: The zero-crossing detection signal is received from the driving circuit in the N reverse resistance switching devices.

5. The method for shutting down a DC power transmission converter valve at zero current crossing according to any one of claims 1 to 4, characterized in that: The reverse-blocking switching device comprises a reverse-blocking integrated gate-commutated thyristor IGCT.

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