A direct current transmission converter valve trigger signal control system and method

Abstract

The present application belongs to the technical field of valve control of DC transmission converter valve, and particularly relates to a DC transmission converter valve trigger signal control system and method thereof. Specifically, the system comprises a main control module, a level conversion module, a gate control module and a laser drive module. The main control module calculates and outputs a drive code signal according to a feedback signal, controls the switching of MOS tubes in the gate control module after the drive code signal is converted into a high-level signal by the level conversion module, and outputs a voltage signal with a required amplitude. The MOS tubes in the laser drive module control the drive current of laser diodes according to the voltage signal, and the thyristor is driven to conduct by the laser signal with the required light power intensity obtained through the change of the drive current. The system effectively solves the problem of single light power intensity of the trigger signal of the existing DC transmission converter valve, and cannot adapt to the triggering of thyristors under different working conditions. Moreover, the system has strong universality and compatibility, and is conducive to promoting the platform design of the valve control of the converter valve.

Description

Technical Field

[0001] This invention belongs to the field of DC transmission converter valve control technology, specifically relating to a DC transmission converter valve trigger signal control system and method. Background Technology

[0002] Ultra-high voltage direct current (UHVDC) transmission refers to direct current transmission at voltage levels of ±800kV and above, and related technologies. In recent years, UHVDC technology has developed rapidly, and several UHVDC transmission projects have been built and put into operation in China.

[0003] The converter valve is a core component of DC power transmission, and its valve control equipment is the control and monitoring unit. The stability and reliability of this equipment directly determine the availability of the DC power transmission system. The valve control equipment and the converter valve assembly triggering channel utilize a laser diode output signal to control the thyristor triggering. The performance of the valve-controlled laser diode determines the reliable triggering of the thyristor, affecting the stability of the DC power transmission system. Therefore, this component is required to have high power, miniaturization, high electro-optical conversion efficiency, stable performance, and strong signal consistency.

[0004] Because the laser signal output by the laser diode needs to pass through a long optical fiber and an optical distributor before reaching the thyristor of the converter valve, there are inconsistencies in the intermediate links. Furthermore, the laser diode will experience attenuation during years of operation. However, existing methods cannot accurately locate the degree of attenuation of the optical power of a particular laser diode, and cannot send a precise trigger signal for the DC transmission converter valve, thus failing to guarantee the stable operation of the DC system. Summary of the Invention

[0005] The purpose of this invention is to provide a DC power transmission converter valve trigger signal control system and method to solve the problem of the single and inaccurate trigger signal output from the laser diode to the converter valve thyristor.

[0006] To address the aforementioned technical problems, this invention provides a DC transmission converter valve trigger signal control system, characterized by comprising a main control module, a gate-level control module, and a laser drive module. The gate-level control module includes a voltage divider branch with multiple voltage divider resistors connected in series. The high-voltage terminals of each voltage divider resistor are connected to the output terminal of the gate control module via voltage control switches. The laser drive module includes a laser drive switch and a laser diode connected in series, with the control terminal of the laser drive switch connected to the output terminal of the gate control module. The main control module controls the various voltage control switches, selectively turning on one of them to allow the gate control module to output the required voltage signal to control the laser drive switch to turn on, thereby adjusting the current flowing through the laser diode to obtain the desired optical power signal.

[0007] Its beneficial effects are as follows: To solve the problem of inaccurate trigger signals from the laser diode to the thyristor of the converter valve, the system of this invention outputs the required voltage signal from the gate control module to the laser drive module based on the signal output by the main control module, thereby controlling the current flowing through the laser diode and obtaining the optical power of the laser diode required to trigger the thyristor. This system effectively solves the problem that the existing DC transmission converter valve trigger signal optical power intensity is singular and cannot adapt to thyristor triggering under different operating conditions. It also has strong versatility and compatibility, which is conducive to promoting the platform-based design of converter valve control.

[0008] Furthermore, it also includes a level conversion module, which converts low-level signals into high-level signals. The main control module controls the connected voltage control switches through the level conversion module.

[0009] Its beneficial effects are: converting low-level electrical signals into high-level signals is beneficial for controlling the various MOS transistors in the gate control module, so as to control the output signal required, which is an important basis for accurately triggering thyristors.

[0010] Furthermore, the high-voltage end of each voltage divider resistor is grounded through its own parallel-connected filter capacitor and energy storage capacitor.

[0011] Its beneficial effects are: it can be used to filter circuits and store electrical energy on the line when the corresponding MOS transistor is not conducting, making the system cost lower and the reliability higher, which is conducive to promoting the platform design of converter valve control.

[0012] Furthermore, the anode of the laser diode is grounded through a filter capacitor and an energy storage capacitor connected in parallel.

[0013] Its beneficial effects are: it can be used to filter circuits and store electrical energy on the line when the corresponding MOS transistor is not conducting, making the system cost lower and the reliability higher, which is conducive to promoting the platform design of converter valve control.

[0014] Furthermore, both the voltage-controlled switch and the laser-driven switch are MOSFETs.

[0015] Its beneficial effects are: controlling the conduction of the branch is an important control device for obtaining the optical power required by the laser diode, making the output optical power of the laser diode more accurate, more applicable, and more efficient.

[0016] Furthermore, the laser driving module also includes a transistor and a diode. The output terminal of the gate control module is connected to the gate of the laser driving switch through the diode, and the anode of the diode is connected to the output terminal of the gate control module. The transistor is connected in series between the gate and source of the laser driving switch, and the base of the transistor is connected to the anode of the diode.

[0017] Its beneficial effects are: the diode is used to prevent current from flowing from the gate of the MOSFET to the output of the gate-level control module when the energy storage capacitor discharges through the transistor, making the system more adaptable, more reliable and more powerful.

[0018] Furthermore, the main control module can be any logic processing chip among MCU, FPGA, or single-chip microcomputer.

[0019] To address the aforementioned technical problems, this invention also provides a method for controlling the trigger signal of a DC transmission converter valve. The optical signal fed back from the converter valve is input into the DC transmission converter valve trigger signal control system for processing to adjust the current flowing through the laser diode, thereby obtaining the desired optical power signal. The control system includes a main control module, a gate-level control module, and a laser drive module. The gate-level control module includes a voltage divider branch with multiple voltage divider resistors connected in series. The high-voltage terminals of each voltage divider resistor are connected to the output terminal of the gate control module via voltage control switches. The laser drive module includes a laser drive switch and a laser diode connected in series. The control terminal of the laser drive switch is connected to the output terminal of the gate control module. The main control module controls the connected voltage control switches, calculating and outputting a drive encoding signal to the gate control module based on the feedback signal. This causes the gate control module to control a specific voltage control switch to conduct, thereby outputting the required voltage signal to control the laser drive switch to conduct, thus adjusting the current flowing through the laser diode.

[0020] Its beneficial effects are as follows: To solve the problem of inaccurate trigger signal output from laser diode to thyristor of converter valve, the method of this invention, based on the trigger signal control system of DC transmission converter valve, outputs the required voltage signal from gate control module to laser drive module according to the signal output from main control module, so as to control the current flowing through laser diode and obtain the optical power of laser diode required to trigger thyristor. It effectively solves the problem that the optical power intensity of trigger signal of existing DC transmission converter valve is single and cannot adapt to thyristor triggering under different operating conditions, making the output optical power of laser diode more accurate, and also has strong versatility and compatibility, which is conducive to promoting the platform design of converter valve control.

[0021] Furthermore, the specific method for calculating and outputting a drive encoding signal to the gate-level control module based on the feedback signal, so that the gate-level control module controls the corresponding voltage control switch to turn on, is as follows: the required optical power is determined by analyzing the feedback signal; the PI curve of the laser diode is looked up based on the optical power value to determine the drive current of the laser diode; the on-state voltage of the laser drive switch corresponding to the drive current is then found; the required output voltage value of the gate-level control module is calculated; and the voltage control switch is turned on based on the required output voltage value of the gate-level control module. Attached Figure Description

[0022] Figure 1 This is a structural diagram of the DC power transmission converter valve control device of the present invention;

[0023] Figure 2 This is a schematic diagram of the DC power transmission converter valve trigger signal control system of the present invention. Detailed Implementation

[0024] The basic concept of this invention is as follows: based on the feedback signal indicating the required optical power intensity for triggering the thyristor, the optical power of the laser diode is precisely adjusted to achieve precise triggering of the thyristor by the converter valve. Specifically, during laser diode adjustment, the drive encoding signal output from the main control module is first amplified by the level conversion module in the trigger signal control system. This amplification controls the voltage control switch in the control module to output different voltage values. These different voltage values, combined with the laser drive switch in the laser drive module, control the current flowing through the laser diode, thereby controlling the optical power intensity. Based on this concept, a DC transmission converter valve trigger signal control system and a DC transmission converter valve trigger signal control method can be implemented.

[0025] The present invention will now be described in detail with reference to the accompanying drawings and method embodiments.

[0026] Example of DC transmission converter valve trigger signal control method:

[0027] refer to Figure 1 The diagram shows a structure including a valve assembly and a converter valve control system. The valve assembly sends a feedback signal with the required optical power intensity to the converter valve control system, which receives the feedback signal. A DC transmission converter valve trigger signal control method of the present invention specifically includes: the main control module in the aforementioned converter valve control system calculates and outputs a drive encoding signal to the voltage control switch control terminal in the gate-level control module based on the feedback signal, thereby controlling one of all voltage control switches to be selectively turned on, so as to output the voltage signal of the high-voltage side of the required voltage divider resistor on the voltage divider branch to the laser drive module. The laser drive switch in the laser drive module controls the drive current flowing through the laser diode according to the obtained voltage signal, and the laser signal with the required optical power intensity is obtained by the change of the drive current.

[0028] In the aforementioned DC transmission converter valve trigger signal control method, to solve the problem of inaccurate trigger signal output from the laser diode to the converter valve thyristor, a DC transmission converter valve trigger signal control system of the present invention is used to process the feedback signal. The system schematic diagram is shown below. Figure 2 As shown, it includes a main control module, a level conversion module, a gate-level control module, and a laser drive module.

[0029] The main control module is used to calculate and output drive encoding signals based on feedback signals to control the voltage control switches (MOSFETs Q1 to Q) in the gate control module. n In this embodiment, a MOS transistor is selected to conduct; the main control module can be a logic processing chip such as an MCU, FPGA, or single-chip microcomputer.

[0030] The level conversion module includes a level conversion chip U1, which is used to convert the output of the main control module from a low level to a high level signal; the level conversion module can be an interface chip or a driver manager or other logic device that can provide level conversion.

[0031] The gate-level control module includes a branch with one end connected to the power supply and the other end grounded. This branch is connected in series with multiple voltage divider resistors (R1~R2). n Each voltage divider resistor corresponds to a voltage control switch. Each voltage control switch is connected in series between the high-voltage side of its corresponding resistor and the output of the gate control module. The control terminal of the voltage control switch is connected to the output of the level conversion module. The high-voltage side of each voltage divider resistor in the gate control module is also grounded through its own parallel filter capacitor and energy storage capacitor. For example, the high-voltage side of R1 is grounded through its corresponding parallel filter capacitor (C1) and energy storage capacitor (e1).

[0032] The laser driving module includes a branch connected to the power supply at one end and ground at the other end. A laser driving switch (MOSFET Q0, a MOSFET is selected in this embodiment) and a laser diode (LD) are connected in series on this branch. The gate of MOSFET Q0 is connected to the output terminal of the gate control module. The anode of the laser diode in the laser driving module is grounded through a filter capacitor and an energy storage capacitor connected in parallel. The laser driving module also includes a transistor (T1) and a diode. The output terminal of the gate control module is connected to the gate of MOSFET Q0 through the diode, and the anode is connected to the output terminal of the gate control module. The transistor is connected in series between the gate and source of MOSFET Q0, and the base of the transistor is connected to the anode of the diode.

[0033] The specific processing steps of the above system are as follows:

[0034] After the main control module outputs the drive encoding signal, the low voltage is converted to a high voltage level by the level conversion module to control the switching on and off of the MOSFET in the gate control module. This is used to input high or low level signals to the laser driver module. When the signal output by the gate control module is high, T1 in the laser driver module is not turned on. At this time, the equivalent capacitance at the input terminal of MOSFET Q0 is charged, MOSFET Q0 is turned on, and the laser diode emits light. When the signal output by the gate control module is low, transistor T1 in the laser driver module is turned on, and the equivalent capacitance at the source of MOSFET Q0 is discharged through T1. The switching on and off action of MOSFET Q0 controls whether the laser diode emits light or not.

[0035] Taking a gate-level control module consisting of two sets of controllable resistor voltage divider circuits as an example:

[0036] By controlling the turn-on of the first MOSFET Q1 and the turn-off of the second MOSFET Q2, the power supply can be configured to perform gate-level control of the laser drive module without a resistor divider circuit; since the drain-source voltage (V) is in the constant current region when MOSFET Q0 is operating, ds The increased portion is almost entirely used to overcome the resistance of the pinch-off region to the drain current, I d Almost no due to V ds It changes with the increase of I d It depends almost entirely on the gate-source voltage (V) gs ), corresponding to each V gs There is a definite I d At this point, I can be used d Considered as voltage V gs The controlled current source; therefore, it can be equivalent to the V0 of the MOSFET Q0 in the laser drive module. gs Control the drive current I of the laser diode d The V obtained at this time gs Maximum, I d The maximum output power of the laser diode is obtained by maximizing the output power of the laser diode.

[0037] Similarly, by turning off the first MOSFET Q1 and turning on the second MOSFET Q2 in the gate-level control module, the power supply can be configured to use the voltage signal obtained after voltage division by the resistor divider circuit (R1 and R2) for gate-level control of the laser driver module. This is equivalent to the voltage of MOSFET Q0 in the laser driver module. gs Control the drive current I of the laser diode d The V obtained at this time gs To be the minimum, I d The minimum value is obtained, which in turn results in the minimum output power of the laser diode.

[0038] However, the gate-level control module contains n (n≥2) sets of controllable resistor voltage divider circuits. By controlling the on / off state of its MOSFETs, various resistor voltage divider circuits can be configured to obtain voltage signals of different amplitudes. These voltage signals of different amplitudes can be equivalent to the V0 of the MOSFET Q0 in the laser driver module. gs Control the drive current I of the laser diode d Through I d The change can be used to drive the thyristor to conduct by laser signals with different optical power intensities.

[0039] Upon receiving the feedback signal, the main control module analyzes and determines the required optical power to trigger the converter valve. Based on this optical power value, it queries the PI curve in the laser diode datasheet and then adjusts the diode's drive current Ii. d Confirm, then find the MOSFET datasheet and select I. d V in the constant current region gs This allows for the calculation of the required output voltage (V) of the gate module. g The calculation formula is: V g ≈I d *+V gs By controlling Q1 to Q n By turning it on and off, different V values ​​can be obtained. g For example: control that all MOSFETs except Q2 are turned on are turned off, V g The value is 15V voltage minus the diode voltage drop, and then through R1 and R2+R3+…R… n The pressure is determined by the pressure distribution.

[0040] This invention has the advantages of wider applicability, higher reliability, more powerful functions and lower cost. It effectively solves the problem that the trigger signal optical power intensity of existing DC transmission converter valves is single and cannot adapt to thyristor triggering under different operating conditions. It also has strong versatility and compatibility, which is conducive to promoting the platform-based design of converter valve control.

[0041] Example of a DC power transmission converter valve trigger signal control system:

[0042] The present invention provides a DC transmission converter valve trigger signal control system, the specific structure of which has been described in detail in the embodiments of the DC transmission converter valve trigger signal control method, and will not be repeated here.

Claims

1. A DC transmission converter valve trigger signal control system, characterized in that, It includes a main control module, a gate-level control module, and a laser driver module. The gate-level control module includes a voltage divider branch with multiple voltage divider resistors connected in series. The high-voltage terminals of each voltage divider resistor are connected to the output terminal of the gate control module via voltage control switches. The laser driver module includes a laser driver switch and a laser diode connected in series. The control terminal of the laser driver switch is connected to the output terminal of the gate control module. The main control module controls the voltage control switches, selectively turning on one of them so that the gate control module outputs the required voltage signal to control the laser driver switch to turn on, thereby adjusting the current flowing through the laser diode and obtaining the required optical power signal.

2. The DC transmission converter valve trigger signal control system according to claim 1, characterized in that, It also includes a level conversion module, which is used to convert low-level signals to high-level signals. The main control module controls the connected voltage control switches through the level conversion module.

3. The DC transmission converter valve trigger signal control system according to claim 1, characterized in that, The high-voltage end of each voltage divider resistor is also grounded through its own parallel-connected filter capacitor and energy storage capacitor.

4. The DC transmission converter valve trigger signal control system according to claim 1, characterized in that, The anode of the laser diode is grounded through a filter capacitor and an energy storage capacitor connected in parallel.

5. The DC transmission converter valve trigger signal control system according to claim 1, characterized in that, Both the voltage-controlled switch and the laser-driven switch are MOSFETs.

6. The DC transmission converter valve trigger signal control system according to claim 5, characterized in that, The laser driving module also includes a transistor and a diode. The output of the gate control module is connected to the gate of the laser driving switch through the diode, and the anode of the diode is connected to the output of the gate control module. The transistor is connected in series between the gate and source of the laser driving switch, and the base of the transistor is connected to the anode of the diode.

7. The DC transmission converter valve trigger signal control system according to claim 1, characterized in that, The main control module can be any logic processing chip among MCU, FPGA or single-chip microcomputer.

8. A method for controlling the trigger signal of a DC transmission converter valve, characterized in that, The optical signal fed back from the converter valve is input into the DC transmission converter valve trigger signal control system for processing to adjust the current flowing through the laser diode and obtain the required optical power signal. The control system includes a main control module, a gate-level control module, and a laser drive module. The gate-level control module includes a voltage divider branch with multiple voltage divider resistors connected in series. The high-voltage terminals of each voltage divider resistor are connected to the output terminal of the gate control module via voltage control switches. The laser drive module includes a laser drive switch and a laser diode connected in series. The control terminal of the laser drive switch is connected to the output terminal of the gate control module. The main control module controls the connected voltage control switches, calculates and outputs a drive encoding signal to the gate control module based on the feedback signal, causing the gate control module to control a corresponding voltage control switch to conduct. This, in turn, causes the gate control module to output the required voltage signal to control the laser drive switch to conduct, thereby adjusting the current flowing through the laser diode.

9. The DC transmission converter valve trigger signal control method according to claim 8, characterized in that, The specific method by which the gate-level control module calculates and outputs a drive encoding signal to the gate-level control module based on the feedback signal, so that the gate-level control module controls the conduction of a certain voltage control switch, is as follows: the required optical power is determined by analyzing the feedback signal; the PI curve of the laser diode is looked up based on the optical power value to determine the drive current of the laser diode; the conduction voltage of the laser drive switch corresponding to the drive current is then found; and the required output voltage value of the gate-level control module is calculated. The voltage control switch is then controlled to conduct based on the required output voltage value of the gate-level control module.

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