An adaptive current clipping control method for voltage source converters

Abstract

This invention discloses an adaptive current limiting control method for a voltage source converter, comprising the following steps: obtaining the converter's active power, grid connection point voltage, and output current; calculating the d-axis and q-axis components of the converter's grid connection point voltage and output current in the dq rotating coordinate system; calculating the phase reference value of the converter's AC side; calculating the d-axis and q-axis reference values ​​of the converter's output current after adaptive current limiting control based on the maximum allowable value and actual value of the converter's output current; calculating the d-axis and q-axis reference values ​​of the modulation voltage at the converter's output; and calculating the reference value of the modulation voltage at the converter's output in the abc stationary coordinate system. This invention introduces an adaptive coefficient into the converter's current limiting stage, enabling the converter to adjust the magnitude of the d-axis and q-axis current components of the limited output current according to demand. Simultaneously, it improves the dynamic characteristics after system faults, allowing the converter to automatically recover to normal voltage control mode after fault clearance.

Description

Technical Field

[0001] This invention belongs to the field of voltage source converter control technology, specifically relating to an adaptive current limiting control method for voltage source converters. Background Technology

[0002] Currently, most new energy voltages are connected to the grid via converters. Unlike synchronous generators, voltage source converters achieve synchronization with the grid through control. Furthermore, voltage source converters are composed of power electronic equipment and have poor overcurrent capacity. Therefore, current limiting mechanisms are needed in converter control to limit the converter's output current. Existing current limiting methods can be mainly divided into direct current limiting and virtual impedance current limiting. The virtual impedance current limiting method introduces virtual resistance and virtual reactance to limit the converter's grid connection point voltage, thereby limiting the output current amplitude. It retains the external characteristics of the converter's voltage source under fault conditions and has good transient stability, but its current limiting effect is not as good as the direct current limiting method.

[0003] The direct current limiting method limits the output current amplitude by limiting the current reference value, and its limiting effect is good. However, if the current limiting method is not designed properly, the converter may still be unable to exit the limiting control mode on its own under certain operating conditions, even if the fault is cleared in time.

[0004] Therefore, there is an urgent need for a current limiting control method that allows the converter to automatically exit the limiting control mode under various operating conditions, regardless of whether the fault is cleared in time. Summary of the Invention

[0005] The main objective of this invention is to address the problem that, under certain operating conditions, even if the fault is promptly cleared using the existing direct current limiting method, the converter still cannot automatically exit the current limiting control mode. This invention proposes an adaptive current limiting control method for voltage source converters. This method can adaptively adjust the d-axis and q-axis components of the converter output current under the current limiting state according to requirements, while simultaneously improving the dynamic characteristics of the power system under large disturbance faults, ensuring that the converter can automatically recover to normal voltage control mode under various operating conditions.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] An adaptive current limiting control method for a voltage source converter includes the following steps:

[0008] S1. Obtain the reference and actual values ​​of active power of voltage source converter in the power system, obtain the reference and actual values ​​of grid connection point voltage, and obtain the maximum allowable value and actual value of converter output current.

[0009] S2. Calculate the d-axis and q-axis components of the converter grid connection point voltage and the converter output current in the dq rotating coordinate system;

[0010] S3. Calculate the phase reference value on the AC side of the converter;

[0011] S4. Calculate the d-axis reference value and q-axis reference value of the converter output current in the dq rotating coordinate system;

[0012] S5. Based on the maximum allowable value and the actual value of the converter output current, calculate the reference values ​​of the d-axis current and q-axis current in the dq rotating coordinate system after the converter output current is limited and controlled.

[0013] S6. Calculate the reference values ​​of the modulation voltage at the AC output of the converter in the d-axis and q-axis rotating coordinate system.

[0014] S7. Calculate the reference values ​​of the modulation voltage at the AC output of the converter in the a-axis, b-axis, and c-axis coordinate system.

[0015] S8. Based on the phase reference value of the AC side of the converter and the reference value of the modulation voltage in the dq rotating coordinate system, the corresponding control pulses are generated using pulse width modulation theory to realize the control of the converter.

[0016] Furthermore, in step S2, the d-axis component E of the converter grid connection point voltage in the dq coordinate system... d and q-axis component E q The calculation formula is as follows:

[0017]

[0018] Among them, E a E b E c Let θ represent the a-axis, b-axis, and c-axis components of the converter grid connection point voltage in the abc coordinate system. * This is the phase reference value for the AC side of the converter; after dq decomposition, the alternating grid connection point voltage in the abc coordinate system can be converted into the DC value in the dq coordinate system, which facilitates subsequent control.

[0019] The d-axis component I of the converter output current in the dq coordinate system d and q-axis component I q The calculation formula is as follows:

[0020]

[0021] Among them, I a I b I cLet A, B, and C be the components of the converter output current in the abc coordinate system. Using the Park transformation described above, the grid-connected voltage and the d-axis and q-axis components of the converter output current can be determined.

[0022] Furthermore, in step S3, the phase reference value θ on the AC side of the converter... * The calculation formula is as follows:

[0023]

[0024] Where s is the Laplace operator, ω0 is the synchronous angular frequency of the AC power grid, J and D are the power virtual inertia and damping coefficient, respectively, and P ref P represents the reference value of the converter's output active power, and P represents the actual value of the converter's output active power. The phase angle reference value on the AC side of the converter can be obtained using the control law described above. In step S3, the control equation actively constructs the system frequency by simulating the rotor motion equation of a traditional synchronous generator, thus achieving active support for the grid frequency.

[0025] Furthermore, in step S4, the d-axis reference value of the converter AC output current... and q-axis reference value The calculation formula is as follows:

[0026]

[0027] Among them, K PV and K IV These are the proportional and integral parameters of the voltage controller, E ref E is a reference value for the grid voltage amplitude. d E represents the d-axis voltage component at the converter grid connection point. q This represents the q-axis voltage component at the converter's grid connection point. Using the control law described above, the d-axis and q-axis components of the converter output current reference value can be obtained. The main purpose of obtaining the dq-axis reference values ​​of the converter output current is to facilitate subsequent current limiting control to restrict it, thereby preventing the converter output current from exceeding its maximum value.

[0028] Furthermore, in step S5, the converter output current, after being limited and controlled, is the d-axis reference value in the dq rotating coordinate system. and q-axis reference value The calculation formula is as follows:

[0029]

[0030] Where λ is the adaptive coefficient, I maxThis represents the maximum allowable output current of the converter. Using the current limiting control method described above, the d-axis and q-axis components of the converter output current under limiting conditions can be adjusted as needed to obtain the d-axis and q-axis components of the converter output current reference value after current limiting control. Adaptive limiting control has two main functions: first, it limits the converter output current to prevent damage to the converter's internal power electronic components from exceeding the limit; second, it uses adaptive coefficients to flexibly change the dq-axis components of the output current under limiting conditions, adjusting the power angle curve of the converter under limiting conditions and improving the dynamic characteristics of the system during fault processes. Furthermore, by appropriately selecting the adaptive coefficients, it avoids the shortcomings of traditional current limiting control—namely, "locking" in current limiting mode after fault clearance, ensuring that the converter can automatically return to normal voltage control mode after fault clearance.

[0031] Furthermore, in step S6, the reference value of the modulation voltage at the converter outlet along the d-axis in the dq rotating coordinate system. and q-axis voltage reference value The calculation formula is as follows:

[0032]

[0033] Among them, E ref This is a reference value for the grid voltage amplitude. and These are the d-axis and q-axis reference values ​​for the AC output current of the converter, respectively. d and I q These represent the d-axis and q-axis components of the converter output current in the dq rotating coordinate system, respectively, where ω is the actual angular velocity of the power grid, and L... F K represents the inductance value of the LC filter on the AC side of the converter. PC and K IC These are the proportional and integral parameters of the current controller. Using the control laws described above, the d-axis and q-axis components of the modulation voltage at the converter outlet can be obtained; this step is the traditional inner-loop PI control of the current. Performing a Parker transformation on the dq-axis components of the modulation voltage yields the three-phase voltage components in the abc coordinate system, which is the modulation wave of the modulator.

[0034] Furthermore, in step S7, the reference value of the modulation voltage at the converter outlet along the a-axis in the abc stationary coordinate system. b-axis voltage reference value and c-axis voltage reference value The calculation formula is as follows:

[0035]

[0036] Where, θ *This is the phase reference value on the AC side of the converter. and These are the d-axis voltage reference value and q-axis voltage reference value of the modulation voltage at the converter outlet, respectively.

[0037] Since the control signal ultimately required for converter modulation is a voltage modulation wave in the abc stationary coordinate system, it is necessary to convert the d-axis and q-axis voltage reference values ​​of the modulation voltage to the abc stationary coordinate system. Once the output voltage modulation wave is obtained, it can be input to the modulator for pulse width modulation, thereby generating the trigger signal for the converter IGBT and controlling its on / off state.

[0038] Furthermore, in step S8, the process of generating the corresponding control pulse using pulse width modulation theory is as follows:

[0039] S81. Set the reference value of the modulated voltage at the converter outlet on the a-axis of the a-axis in the abc stationary coordinate system. b-axis voltage reference value and c-axis voltage reference value By comparing with the triangular carrier wave, the trigger signals Tg1r and Tg2r of the upper and lower bridge arm IGBTs of phase a, the trigger signals Tg3r and Tg4r of the upper and lower bridge arm IGBTs of phase b, and the trigger signals Tg5r and Tg6r of the upper and lower bridge arm IGBTs of phase c are obtained.

[0040] S82. Use trigger signals Tg1r, Tg2r, Tg3r, Tg4r, Tg5r, and Tg6r to control the turn-on and turn-off of the corresponding IGBTs, so that the converter outputs a narrow rectangular pulse. Then, using the principle of equal area, when the frequency of the triangular carrier is large, the narrow rectangular pulse approaches the sine wave.

[0041] The voltage source converter is controlled by triggering the converter switching devices with the generated pulses. After the above control, when the converter output current is less than the maximum allowable value, the converter is in normal operation mode and the current limiting control does not work, and the converter is equivalent to a controlled voltage source externally. When the converter output current is greater than the maximum allowable value, the converter is in current limiting mode, and the current limiting control limits the amplitude of the converter output current to the maximum value. At this time, the converter is equivalent to a controlled current source externally.

[0042] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0043] (1) This invention allows for the free adjustment of the d-axis and q-axis components of the converter output current after current limiting, based on requirements. When the adaptive coefficient is 1, the limiting method is equivalent to the d-axis priority limiting control method; when the adaptive coefficient is 0, the limiting method is equivalent to the q-axis priority limiting control method. When the adaptive coefficient is within the range of (0,1), a larger adaptive coefficient value results in a larger d-axis current and a smaller q-axis current. In actual operation, the adaptive coefficient can be adjusted according to the actual active and reactive current requirements of the system to actively allocate the d and q-axis currents to obtain optimal performance. Typically, the adaptive coefficient is close to or equal to 1, at which point the system can output the maximum active current under limiting conditions, thus prioritizing the active power transmission of the converter. When the system's reactive power support is insufficient, the adaptive coefficient value is reduced, allowing the system to obtain a larger reactive current under limiting conditions, providing better reactive voltage support for the system.

[0044] (2) Traditional d-axis priority limiting control and q-axis priority limiting control methods suffer from the drawback that the converter cannot automatically exit the limiting control mode when the grid voltage drop fault is cleared. To address this drawback, this invention flexibly adjusts the power angle curve of the system under limiting conditions by changing the adaptive coefficient value, thereby improving the dynamic characteristics of the system under fault conditions and ensuring that the converter returns to normal voltage control mode after the fault is cleared. Moreover, the smaller the adaptive coefficient value, the greater the rightward shift of the power angle curve under limiting conditions, which reduces the acceleration area and increases the deceleration area of ​​the system, thus improving the transient stability of the system. Attached Figure Description

[0045] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0046] Figure 1 This is a flowchart of the adaptive current limiting control method for voltage source converters disclosed in this invention;

[0047] Figure 2 This is a comparative simulation waveform diagram of the adaptive current limiting control method of the voltage source converter of the present invention and the traditional d-axis priority limiting control method in Embodiment 2 of the present invention under the condition that the grid voltage drops to 0.6 pu and the fault is cleared in time.

[0048] Figure 3This is a comparative simulation waveform diagram of the adaptive current limiting control method of the voltage source converter of the present invention and the traditional d-axis priority limiting control method in Embodiment 2 of the present invention under the condition that the grid voltage drops to 0.6 pu and the fault is not cleared in time.

[0049] Figure 4 This is a schematic diagram of the fault clearing situation of the traditional d-axis priority limiting control method and the adaptive current limiting control method in Embodiment 3 of the present invention. Detailed Implementation

[0050] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present application without creative effort are within the scope of protection of the present application.

[0051] In this application, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this application can be combined with other embodiments.

[0052] Example 1

[0053] See Figure 1 This embodiment discloses an adaptive current limiting control method for a voltage source converter, comprising the following steps:

[0054] S1. Obtain the reference and actual values ​​of the converter's active power, the reference and actual values ​​of the grid connection point voltage, and the maximum allowable value and actual value of the converter's output current.

[0055] S2. Calculate the d-axis and q-axis components of the converter grid connection point voltage and the converter output current in the dq rotating coordinate system;

[0056] Among them, the d-axis component E of the converter grid connection point voltage in the dq coordinate system d and q-axis component E q The calculation formula is as follows:

[0057]

[0058] Among them, E a E b E cLet θ represent the a-axis, b-axis, and c-axis components of the converter grid connection point voltage in the abc coordinate system. * This is the phase reference value for the AC side of the converter.

[0059] Among them, the d-axis component I of the converter output current in the dq coordinate system d and q-axis component I q The calculation formula is as follows:

[0060]

[0061] Among them, I a I b I c Let a, b, and c be the components of the converter output current in the abc coordinate system.

[0062] S3. Calculate the phase reference value on the AC side of the converter;

[0063] Among them, the phase reference value θ on the AC side of the converter * The calculation formula is as follows:

[0064]

[0065] Where s is the Laplace operator, ω0 is the synchronous angular frequency of the AC power grid, J and D are the power virtual inertia and damping coefficient, respectively, and P ref P is the reference value of the converter output active power, and P is the actual value of the converter output active power.

[0066] S4. Calculate the reference values ​​for the d-axis current and q-axis current at the converter grid connection point;

[0067] Among them, the d-axis current reference value at the converter grid connection point and q-axis current reference value The calculation formula is as follows:

[0068]

[0069] Among them, K PV and K IV These are the proportional and integral parameters of the voltage controller, E ref E is a reference value for the grid voltage amplitude. d E represents the d-axis voltage component at the converter grid connection point. q This represents the q-axis voltage component at the converter grid connection point.

[0070] S5. Calculate the d-axis and q-axis reference values ​​of the converter output current after limiting control;

[0071] The current limiting control method is as follows:

[0072]

[0073] in, and These represent the d-axis and q-axis reference values ​​of the converter output current after limiting control, respectively, where λ is the adaptive coefficient, and I... max This represents the maximum allowable output current of the converter.

[0074] S6. Calculate the reference values ​​of the modulation voltage at the AC output of the converter in the d-axis and q-axis coordinate system.

[0075] Among them, the d-axis voltage reference value of the modulation voltage at the converter outlet and q-axis voltage reference value The calculation formula is as follows:

[0076]

[0077] Among them, I d and I q These represent the d-axis and q-axis components of the converter output current in the dq rotating coordinate system, respectively, where ω is the actual angular velocity of the power grid, and L... F K represents the inductance value of the LC filter on the AC side of the converter. PC and K IC These are the proportional and integral parameters of the current controller, respectively.

[0078] S7. Calculate the reference values ​​of the modulation voltage at the AC output of the converter in the a-axis, b-axis, and c-axis coordinate system.

[0079] Among them, the reference value of the modulation voltage at the converter outlet on the a-axis in the abc stationary coordinate system. b-axis voltage reference value and c-axis voltage reference value The calculation formula is as follows:

[0080]

[0081] Where, θ * This is the phase reference value on the AC side of the converter. and These are the d-axis voltage reference value and q-axis voltage reference value of the modulation voltage at the converter outlet, respectively.

[0082] S8. Based on the reference value of the modulation voltage, the corresponding control pulses are generated using pulse width modulation theory to control the converter.

[0083] The specific process of generating the corresponding control pulses using pulse width modulation theory is as follows:

[0084] S81. The a-axis reference value, b-axis reference value, and c-axis reference value of the modulation voltage at the converter outlet generated in step S7 are compared with the triangular carrier wave to obtain the trigger signals Tg1r and Tg2r of the upper and lower bridge arm IGBTs of phase a, the trigger signals Tg3r and Tg4r of the upper and lower bridge arm IGBTs of phase b, and the trigger signals Tg5r and Tg6r of the upper and lower bridge arm IGBTs of phase c.

[0085] S82. Use trigger signals Tg1r, Tg2r, Tg3r, Tg4r, Tg5r, and Tg6r to control the turn-on and turn-off of the corresponding IGBTs, so that the converter outputs a narrow rectangular pulse. Then, using the principle of equal area, when the frequency of the triangular carrier is large, the narrow rectangular pulse can approximate a sine wave.

[0086] Example 2

[0087] Based on the adaptive current limiting control method for a voltage source converter disclosed in Embodiment 1, this embodiment uses a test system connected to a weak grid with a short-circuit ratio of 2 via a DC power supply through the converter for simulation verification. The converter limiting method adopts the adaptive current limiting control method involved in this invention, and the adaptive coefficient is set to 0.5. The reference value of the active power output of the converter is initially set to 3.5MW (rated capacity of 5MW), and the grid voltage drops from 1pu to 0.6pu at time t = 10.0s. Figure 2 The simulated waveform of the system when the fault is cleared at t = 13.5s is shown. Figure 3 The simulated waveform of the system when the fault is cleared at t = 13.6s. (From the simulation...) Figure 2 and Figure 3 As can be seen, regardless of whether the fault is cleared in time, the converter can exit the limiting control and return to normal operation after the fault is cleared.

[0088] Example 3

[0089] Based on the adaptive current limiting control method for a voltage source converter disclosed in Embodiment 1, this embodiment compares the acceleration area and maximum deceleration area of ​​the present invention with those of the traditional d-axis priority limiting control method at the same voltage drop depth and the same cutoff angle. The adaptive coefficient is set to 0.85, the maximum allowable output current of the converter is 1 p.u., the reference value of the converter active power is 0.7 pu, and the grid voltage is temporarily reduced from the original 1 p.u. to 0.6 pu. Both controls cut off the fault when the power angle reaches 0.66 rad. The system power angle curve is shown below. Figure 4As shown in the figure. Calculations show that the acceleration area of ​​the traditional d-axis priority limiting control method is 0.0549, and the maximum deceleration area is 0.0084; while the acceleration area of ​​the adaptive current limiting control method is 0.0328, and the maximum deceleration area is 0.1383. It can be seen that the adaptive current limiting control method shifts the power angle curve under the limiting state to the right through an adaptive coefficient, resulting in a smaller acceleration area and a larger deceleration area. Therefore, the transient stability performance of the adaptive current limiting control method is superior to that of the traditional current limiting control method.

[0090] Example 4

[0091] This embodiment compares with existing methods, based on an adaptive current limiting control method for a voltage source converter disclosed in Embodiment 1. This embodiment compares the limit cut-off time of this invention with that of the traditional d-axis priority limiting method. The converter active power reference value is set to 0.7 pu, and the grid voltage is temporarily reduced from 1 p.u. to 0.6 pu. Under this condition, the limit cut-off time of the traditional d-axis priority limiting control method is 12.4 s, the limit cut-off time of the adaptive current limiting control method with an adaptive coefficient of 0.85 is 13.3 s, and the limit cut-off time of the adaptive current limiting control method with an adaptive coefficient of 0.25 is also 13.4 s, as shown in Table 1.

[0092] Table 1. Timetable for Limit Resection under Different Control Strategies

[0093] Control strategy Limit resection time / s Adaptive current limiting control method (k=0.25) 13.4 Adaptive current limiting control method (k=0.85) 13.3 Traditional d-axis priority current limiting method 12.4

[0094] As can be seen from Table 1, the limit cut-off time of the traditional d-axis priority current limiting control method is shorter than that of the adaptive current limiting control method, and the limit cut-off time increases when the adaptive coefficient decreases.

[0095] It should be noted that, for the sake of simplicity, the aforementioned method embodiments are all described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, because according to the present invention, some steps can be performed in other orders or simultaneously.

[0096] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0097] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. An adaptive current limiting control method for a voltage source converter, characterized in that, The adaptive current limiting control method includes the following steps: S1. Obtain the reference and actual values ​​of active power of voltage source converter in the power system, obtain the reference and actual values ​​of grid connection point voltage, and obtain the maximum allowable value and actual value of converter output current. S2. Calculate the d-axis and q-axis components of the converter grid connection point voltage and the converter output current in the dq rotating coordinate system; S3. Calculate the phase reference value on the AC side of the converter; S4. Calculate the d-axis reference value of the converter output current in the dq rotating coordinate system. and q-axis reference value S5. Based on the maximum allowable value and actual value of the converter output current, calculate the d-axis current reference value and q-axis current reference value of the converter output current in the dq rotating coordinate system after limiting control; wherein, the d-axis current reference value of the converter output current in the dq rotating coordinate system after limiting control... and q-axis reference value The calculation formula is as follows: Where λ is the adaptive coefficient, I max This represents the maximum allowable output current of the converter. S6. Calculate the reference values ​​of the modulation voltage at the AC output of the converter in the d-axis and q-axis rotating coordinate system. S7. Calculate the reference values ​​of the modulation voltage at the AC output of the converter in the a-axis, b-axis, and c-axis coordinate system. S8. Based on the phase reference value of the AC side of the converter and the reference value of the modulation voltage in the dq rotating coordinate system, the corresponding control pulses are generated using pulse width modulation theory to realize the control of the converter.

2. The adaptive current limiting control method for a voltage source converter according to claim 1, characterized in that, In step S2, the d-axis component E of the converter grid connection point voltage in the dq coordinate system is... d and q-axis component E q The calculation formula is as follows: Among them, E a E b E c Let θ represent the a-axis, b-axis, and c-axis components of the converter grid connection point voltage in the abc coordinate system. * This is the phase reference value for the AC side of the converter; The d-axis component I of the converter output current in the dq coordinate system d and q-axis component I q The calculation formula is as follows: Among them, I a I b I c Let a, b, and c be the components of the converter output current in the abc coordinate system.

3. The adaptive current limiting control method for a voltage source converter according to claim 1, characterized in that, In step S3, the phase reference value θ on the AC side of the converter... * The calculation formula is as follows: Where s is the Laplace operator, ω0 is the synchronous angular frequency of the AC power grid, J and D are the power virtual inertia and damping coefficient, respectively, and P ref P is the reference value of the converter output active power, and P is the actual value of the converter output active power.

4. The adaptive current limiting control method for a voltage source converter according to claim 1, characterized in that, In step S4, the d-axis reference value of the converter AC output current. and q-axis reference value The calculation formula is as follows: Among them, K PV and K IV These are the proportional and integral parameters of the voltage controller, E ref E is a reference value for the grid voltage amplitude. d E represents the d-axis voltage component at the converter grid connection point. q This represents the q-axis voltage component at the converter grid connection point.

5. The adaptive current limiting control method for a voltage source converter according to claim 1, characterized in that, In step S6, the reference value of the modulation voltage at the converter outlet along the d-axis in the dq rotating coordinate system is... and q-axis voltage reference value The calculation formula is as follows: Among them, E ref This is a reference value for the grid voltage amplitude. and These are the d-axis and q-axis reference values ​​for the AC output current of the converter, respectively. d and I q These represent the d-axis and q-axis components of the converter output current in the dq rotating coordinate system, respectively, where ω is the actual angular velocity of the power grid, and L... F K represents the inductance value of the LC filter on the AC side of the converter. PC and K IC These are the proportional and integral parameters of the current controller, respectively.

6. The adaptive current limiting control method for a voltage source converter according to claim 1, characterized in that, In step S7, the reference value V of the modulation voltage at the converter outlet along the a-axis in the abc stationary coordinate system is... a * b-axis voltage reference value V b * and c-axis voltage reference value V c * The calculation formula is as follows: Where, θ * This is the phase reference value on the AC side of the converter. and These are the d-axis voltage reference value and q-axis voltage reference value of the modulation voltage at the converter outlet, respectively.

7. The adaptive current limiting control method for a voltage source converter according to claim 1, characterized in that, In step S8, the process of generating the corresponding control pulse using pulse width modulation theory is as follows: S81. The reference value V of the modulated voltage at the converter outlet in the a-axis voltage of the a-axis in the abc stationary coordinate system. a * b-axis voltage reference value V b * and c-axis voltage reference value V c * By comparing with the triangular carrier wave, the trigger signals Tg1r and Tg2r of the upper and lower bridge arm IGBTs of phase a, the trigger signals Tg3r and Tg4r of the upper and lower bridge arm IGBTs of phase b, and the trigger signals Tg5r and Tg6r of the upper and lower bridge arm IGBTs of phase c are obtained. S82. Use trigger signals Tg1r, Tg2r, Tg3r, Tg4r, Tg5r, and Tg6r to control the turn-on and turn-off of the corresponding IGBTs, so that the converter outputs a narrow rectangular pulse. Then, using the principle of equal area, when the frequency of the triangular carrier is large, the narrow rectangular pulse approaches the sine wave.

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