CN-122000979-A - Control method and device of net-structured flexible direct current converter

Abstract

The application provides a control method and a control device of a grid-structured flexible direct current converter. And calculating the phase angle of the grid-connected point according to the actual value of the active power of the grid-connected flexible direct current converter and the actual value of the voltage of the grid-connected point. And calculating the current reference value feedforward quantity of the grid-structured flexible direct current converter according to the actual value of the direct current voltage of the grid-structured flexible direct current converter. And controlling the grid-formed flexible direct current converter according to the phase angle of the grid-connected point and the feedforward quantity of the current reference value. The technical scheme provided by the application can ensure stable control of current sharing at the alternating current side and voltage sharing at the direct current side of the multi-converter valve bank, can realize automatic and accurate power distribution of each converter valve bank without manual intervention under complex working conditions such as random fluctuation of new energy generated power, namely has strong disturbance resistance, can realize stable control of the power grid strength in a wide range, has high reliability, and further improves the reliability of a flexible direct current transmission system.

Inventors

• HAN MINGYUE
• ZHANG FAN
• CHEN XIN
• ZHOU ZHUAN
• BAI XUE
• LI LANFANG
• BIAN JIAYU

Assignees

• 国网电力科学研究院有限公司
• 国网新疆电力有限公司
• 国家电网有限公司
• 中电普瑞电力工程有限公司

Dates

Publication Date

20260508

Application Date

20251230

Claims (20)

1. 1. The control method of the net-structured flexible direct current converter is characterized by comprising the following steps of: calculating the phase angle of the grid-connected point according to the actual value of the active power of the grid-formed flexible direct current converter and the actual value of the voltage of the grid-connected point; Calculating the current reference value feedforward quantity of the grid-structured flexible direct current converter according to the actual direct current voltage value of the grid-structured flexible direct current converter; And controlling the grid-connected flexible direct current converter according to the phase angle of the grid-connected point and the current reference value feedforward quantity.
2. 2. The control method according to claim 1, characterized in that the control method further comprises: performing park transformation on the voltage actual value of the grid-connected point to obtain a d-axis voltage actual value and a q-axis voltage actual value of the grid-connected point; and performing park transformation on the current actual value of the grid-structured flexible direct current converter to obtain a d-axis current actual value and a q-axis current actual value of the grid-structured flexible direct current converter.
3. 3. The control method according to claim 2, wherein the calculating the phase angle of the grid-connected point according to the actual active power value of the grid-connected flexible dc converter and the actual voltage value of the grid-connected point includes: Proportional integral control is carried out on the difference value between the active power reference value of the grid-structured flexible direct current converter and the active power actual value of the grid-structured flexible direct current converter, so that the angular frequency adjustment quantity of the grid-structured flexible direct current converter is obtained; proportional integral control is carried out on the difference value between the q-axis voltage actual value of the grid-connected point and the q-axis voltage reference value of the grid-connected point, so that the angular frequency correction quantity of the grid-structured flexible direct current converter is obtained; Superposing the angular frequency adjustment quantity, the angular frequency correction quantity and the angular frequency reference value of the grid-structured flexible direct current converter to obtain the angular frequency of the grid-connected point; and carrying out integral control on the angular frequency of the grid-connected point to obtain the phase angle of the grid-connected point.
4. 4. The control method according to claim 2, wherein the calculating the current reference feedforward amount of the grid-type flexible dc converter according to the actual dc voltage value of the grid-type flexible dc converter includes: And performing proportional integral control on the difference value between the direct-current voltage reference value of the grid-structured flexible direct-current converter and the direct-current voltage actual value of the grid-structured flexible direct-current converter to obtain the current reference value feedforward quantity.
5. 5. The control method according to claim 2, wherein said controlling the grid-formed flexible dc converter based on the phase angle of the grid-connected point and the current reference feedforward amount comprises: calculating a current reference value of the grid-structured flexible direct current converter according to the reactive power actual value of the grid-structured flexible direct current converter and the voltage actual value of the grid-connected point; calculating a modulation voltage reference value of the grid-connected flexible direct current converter according to the voltage actual value of the grid-connected point, the current reference value of the grid-connected flexible direct current converter and the current reference value feedforward quantity; Performing inverse Peak conversion on the modulation voltage reference value of the grid-connected flexible direct current converter according to the phase angle of the grid-connected point to obtain a modulation signal; and controlling the net-structured flexible direct current converter according to the modulation signal.
6. 6. The control method according to claim 5, wherein the calculating the current reference value of the grid-structured flexible dc converter according to the actual reactive power value of the grid-structured flexible dc converter and the actual voltage value of the grid-connected point includes: Proportional integral control is carried out on the difference value between the reactive power reference value of the grid-structured flexible direct current converter and the reactive power actual value of the grid-structured flexible direct current converter to obtain the d-axis voltage correction quantity of the grid-structured flexible direct current converter, and the d-axis current reference value of the grid-structured flexible direct current converter is calculated according to the d-axis voltage correction quantity of the grid-structured flexible direct current converter, the d-axis voltage actual value of the grid-connected point and the d-axis voltage reference value of the grid-connected point; and performing proportional integral control on the difference value between the q-axis voltage reference value of the grid-connected point and the q-axis voltage actual value of the grid-connected point to obtain the q-axis current reference value of the grid-structured flexible direct current converter under a two-phase rotating coordinate system.
7. 7. The control method according to claim 6, wherein the d-axis current reference value of the mesh-type flexible dc converter satisfies: Wherein, the Representing a d-axis current reference value of the grid-structured flexible direct current converter, Represents the d-axis voltage correction amount of the grid-structured flexible direct current converter, Represents the d-axis voltage reference value of the grid-connected point, Represents the actual value of the d-axis voltage of the grid-connected point, The scale factor is represented by a ratio of, Representing the integral coefficient, s representing the complex variable of the complex frequency domain.
8. 8. The control method according to claim 5, wherein the calculating the modulation voltage reference value of the grid-connected flexible dc converter according to the voltage actual value of the grid-connected point, the current reference value of the grid-connected flexible dc converter, and the current reference value feedforward amount includes: Calculating the d-axis current deviation amount of the grid-structured flexible direct current converter according to the d-axis current reference value, the d-axis voltage actual value and the current reference value feedforward amount of the grid-structured flexible direct current converter; Proportional-integral control is carried out on the d-axis current deviation amount to obtain d-axis first modulation voltage of the grid-structured flexible direct current converter; Calculating the q-axis second modulation voltage of the grid-type flexible direct current converter according to the actual value of the q-axis current of the grid-type flexible direct current converter; Calculating a d-axis modulation voltage reference value of the grid-structured flexible direct current converter according to the d-axis first modulation voltage, the d-axis second modulation voltage and the d-axis voltage actual value of the grid-structured flexible direct current converter, and calculating a q-axis modulation voltage reference value of the grid-structured flexible direct current converter according to the q-axis first modulation voltage, the q-axis second modulation voltage and the q-axis voltage actual value of the grid-structured flexible direct current converter.
9. 9. The control method according to claim 8, wherein, The d-axis current deviation amount of the net-structured flexible direct current converter meets the following conditions: Wherein, the Represents the d-axis current deviation amount of the grid-structured flexible direct current converter, Representing a d-axis current reference value of the grid-structured flexible direct current converter, Representing the actual d-axis voltage value of the grid-structured flexible direct current converter, Representing the current reference feedforward amount.
10. 10. The control method according to claim 8, wherein, The d-axis modulation voltage reference value of the grid-structured flexible direct current converter meets the following conditions: Wherein, the Representing a d-axis modulation voltage reference value of the grid-structured flexible direct current converter; representing the actual d-axis voltage value of the grid-structured flexible direct current converter; representing the d-axis first modulation voltage of the grid-structured flexible direct current converter; the d-axis second modulation voltage of the net-structured flexible direct current converter is expressed to satisfy the following conditions , Representing the q-axis current actual value of the grid-structured flexible direct current converter; the q-axis modulation voltage reference value of the network-structured flexible direct current converter meets the following conditions: Wherein, the Representing a q-axis modulation voltage reference value of the grid-structured flexible direct current converter; representing the q-axis voltage actual value of the grid-structured flexible direct current converter; Representing the q-axis first modulation voltage of the grid-structured flexible direct current converter; the q-axis second modulation voltage of the grid-structured flexible direct current converter is expressed to satisfy the following conditions Omega represents the angular frequency of the alternating current system, L represents the equivalent inductance of the grid-structured flexible direct current converter, And the d-axis current actual value of the grid-structured flexible direct current converter is represented.
11. 11. A control device for a grid-structured flexible dc converter, comprising: the first calculation module is used for calculating the phase angle of the grid-connected point according to the actual value of the active power of the grid-formed flexible direct current converter and the actual value of the voltage of the grid-connected point; The second calculation module is used for calculating the current reference value feedforward quantity of the grid-structured flexible direct current converter according to the actual direct current voltage value of the grid-structured flexible direct current converter; And the control module is used for controlling the grid-connected flexible direct current converter according to the phase angle of the grid-connected point and the current reference value feedforward quantity.
12. 12. The control device according to claim 11, characterized in that it further comprises a transformation module, in particular for: performing park transformation on the voltage actual value of the grid-connected point to obtain a d-axis voltage actual value and a q-axis voltage actual value of the grid-connected point; and performing park transformation on the current actual value of the grid-structured flexible direct current converter to obtain a d-axis current actual value and a q-axis current actual value of the grid-structured flexible direct current converter.
13. 13. The control device of claim 12, wherein the first computing module is specifically configured to: Proportional integral control is carried out on the difference value between the active power reference value of the grid-structured flexible direct current converter and the active power actual value of the grid-structured flexible direct current converter, so that the angular frequency adjustment quantity of the grid-structured flexible direct current converter is obtained; proportional integral control is carried out on the difference value between the q-axis voltage actual value of the grid-connected point and the q-axis voltage reference value of the grid-connected point, so that the angular frequency correction quantity of the grid-structured flexible direct current converter is obtained; Superposing the angular frequency adjustment quantity, the angular frequency correction quantity and the angular frequency reference value of the grid-structured flexible direct current converter to obtain the angular frequency of the grid-connected point; and carrying out integral control on the angular frequency of the grid-connected point to obtain the phase angle of the grid-connected point.
14. 14. The control device according to claim 12, wherein the second calculation module is specifically configured to: And performing proportional integral control on the difference value between the direct-current voltage reference value of the grid-structured flexible direct-current converter and the direct-current voltage actual value of the grid-structured flexible direct-current converter to obtain the current reference value feedforward quantity.
15. 15. The control device according to claim 12, wherein the control module is specifically configured to: calculating a current reference value of the grid-structured flexible direct current converter according to the reactive power actual value of the grid-structured flexible direct current converter and the voltage actual value of the grid-connected point; calculating a modulation voltage reference value of the grid-connected flexible direct current converter according to the voltage actual value of the grid-connected point, the current reference value of the grid-connected flexible direct current converter and the current reference value feedforward quantity; Performing inverse Peak conversion on the modulation voltage reference value of the grid-connected flexible direct current converter according to the phase angle of the grid-connected point to obtain a modulation signal; and controlling the net-structured flexible direct current converter according to the modulation signal.
16. 16. The control device according to claim 15, wherein the control module is specifically configured to: Proportional integral control is carried out on the difference value between the reactive power reference value of the grid-structured flexible direct current converter and the reactive power actual value of the grid-structured flexible direct current converter to obtain the d-axis voltage correction quantity of the grid-structured flexible direct current converter, and the d-axis current reference value of the grid-structured flexible direct current converter is calculated according to the d-axis voltage correction quantity of the grid-structured flexible direct current converter, the d-axis voltage actual value of the grid-connected point and the d-axis voltage reference value of the grid-connected point; and performing proportional integral control on the difference value between the q-axis voltage reference value of the grid-connected point and the q-axis voltage actual value of the grid-connected point to obtain the q-axis current reference value of the grid-structured flexible direct current converter under a two-phase rotating coordinate system.
17. 17. The control device according to claim 16, wherein the d-axis current reference value of the mesh-formed flexible dc converter satisfies: Wherein, the Representing a d-axis current reference value of the grid-structured flexible direct current converter, Represents the d-axis voltage correction amount of the grid-structured flexible direct current converter, Represents the d-axis voltage reference value of the grid-connected point, Represents the actual value of the d-axis voltage of the grid-connected point, The scale factor is represented by a ratio of, Representing the integral coefficient, s representing the complex variable of the complex frequency domain.
18. 18. The control device according to claim 15, wherein the control module is specifically configured to: Calculating the d-axis current deviation amount of the grid-structured flexible direct current converter according to the d-axis current reference value, the d-axis voltage actual value and the current reference value feedforward amount of the grid-structured flexible direct current converter; Proportional-integral control is carried out on the d-axis current deviation amount to obtain d-axis first modulation voltage of the grid-structured flexible direct current converter; Calculating the q-axis second modulation voltage of the grid-type flexible direct current converter according to the actual value of the q-axis current of the grid-type flexible direct current converter; Calculating a d-axis modulation voltage reference value of the grid-structured flexible direct current converter according to the d-axis first modulation voltage, the d-axis second modulation voltage and the d-axis voltage actual value of the grid-structured flexible direct current converter, and calculating a q-axis modulation voltage reference value of the grid-structured flexible direct current converter according to the q-axis first modulation voltage, the q-axis second modulation voltage and the q-axis voltage actual value of the grid-structured flexible direct current converter.
19. 19. The control device of claim 18, wherein the control device comprises a controller, The d-axis current deviation amount of the net-structured flexible direct current converter meets the following conditions: Wherein, the Represents the d-axis current deviation amount of the grid-structured flexible direct current converter, Representing a d-axis current reference value of the grid-structured flexible direct current converter, Representing the actual d-axis voltage value of the grid-structured flexible direct current converter, Representing the current reference feedforward amount.
20. 20. The control device of claim 18, wherein the control device comprises a controller, The d-axis modulation voltage reference value of the grid-structured flexible direct current converter meets the following conditions: Wherein, the Representing a d-axis modulation voltage reference value of the grid-structured flexible direct current converter; representing the actual d-axis voltage value of the grid-structured flexible direct current converter; representing the d-axis first modulation voltage of the grid-structured flexible direct current converter; the d-axis second modulation voltage of the net-structured flexible direct current converter is expressed to satisfy the following conditions , Representing the q-axis current actual value of the grid-structured flexible direct current converter; the q-axis modulation voltage reference value of the network-structured flexible direct current converter meets the following conditions: Wherein, the Representing a q-axis modulation voltage reference value of the grid-structured flexible direct current converter; representing the q-axis voltage actual value of the grid-structured flexible direct current converter; Representing the q-axis first modulation voltage of the grid-structured flexible direct current converter; the q-axis second modulation voltage of the grid-structured flexible direct current converter is expressed to satisfy the following conditions Omega represents the angular frequency of the alternating current system, L represents the equivalent inductance of the grid-structured flexible direct current converter, And the d-axis current actual value of the grid-structured flexible direct current converter is represented.

Description

Control method and device of net-structured flexible direct current converter Technical Field The application relates to the technical field of flexible direct current transmission, in particular to a control method and a device of a grid-structured flexible direct current converter. Background The new energy power generation is connected into a power system through a voltage source converter and the like, so that inertia and damping are reduced, and frequency modulation and voltage regulation capability are reduced. In order to ensure stable operation of the power system, a control strategy with voltage frequency supporting capability becomes a current research hot spot. For voltage source converters, the related art generally implements control by droop control, virtual synchronous machine control (Virtual Synchronous Generator, VSG), or the like. However, as the transmission capacity and the transmission distance are increased, the flexible direct current transmission system is designed according to a multi-station parallel connection and valve bank serial connection structure, so that the alternating current side current sharing and direct current side voltage sharing are realized, the cooperative control among the converter valve banks is realized, and the stable operation of the flexible direct current transmission system under the strength of a wide range power grid is ensured to be one of the current research hot spots. In the related art, one converter valve bank is generally selected for network formation control, and other converter valve banks adopt network following control. However, the automatic power distribution of each converter valve bank is difficult to realize when the power fluctuation of the new energy source is handled, and the overvoltage of a certain converter valve bank can be caused to influence the stable operation of the flexible direct current transmission system. That is, the control method provided by the related art has low reliability, which easily causes that the flexible direct current transmission system cannot stably operate. Disclosure of Invention In order to solve the problems in the prior art, the application provides a control method and a control device of a grid-structured flexible direct current converter. In a first aspect, the present application provides a method for controlling a grid-structured flexible dc converter, which may include: and calculating the phase angle of the grid-connected point according to the actual value of the active power of the grid-connected flexible direct current converter and the actual value of the voltage of the grid-connected point. And calculating the current reference value feedforward quantity of the grid-structured flexible direct current converter according to the actual value of the direct current voltage of the grid-structured flexible direct current converter. And controlling the grid-formed flexible direct current converter according to the phase angle of the grid-connected point and the feedforward quantity of the current reference value. Further, the control method further comprises: and performing park transformation on the actual voltage value of the grid-connected point to obtain the actual d-axis voltage value and the actual q-axis voltage value of the grid-connected point. And performing park transformation on the current actual value of the grid-structured flexible direct current converter to obtain the d-axis current actual value and the q-axis current actual value of the grid-structured flexible direct current converter. In some possible implementations, calculating the phase angle of the grid-connected point according to the actual active power value of the grid-connected flexible direct current converter and the actual voltage value of the grid-connected point includes: And performing proportional integral control on the difference value between the active power reference value of the grid-structured flexible direct current converter and the active power actual value of the grid-structured flexible direct current converter to obtain the angular frequency adjustment quantity of the grid-structured flexible direct current converter. And performing proportional integral control on the difference value between the q-axis voltage actual value of the grid connection point and the q-axis voltage reference value of the grid connection point to obtain the angular frequency correction quantity of the grid-formed flexible direct current converter. And superposing the angular frequency adjustment quantity, the angular frequency correction quantity and the angular frequency reference value of the grid-connected flexible direct current converter to obtain the angular frequency of the grid-connected point. And carrying out integral control on the angular frequency of the grid-connected point to obtain the phase angle of the grid-connected point. In other possible implementations, calculating a current reference feedforwa