Hybrid DC power transmission receiving end VSC and control method thereof, and computer equipment

Abstract

The invention belongs to the technical field of direct-current power transmission, and particularly relates to a hybrid direct-current power transmission receiving end VSC, a control method thereof and computer equipment. The method comprises the following steps: calculating a difference value obtained by subtracting a receiving-end direct-current compaction sampling value from a receiving-end direct-current voltage reference value to obtain a receiving-end direct-current voltage deviation; calculating a difference value obtained by subtracting the receiving-end direct current reference value from the receiving-end direct current actual acquisition value to obtain a receiving-end direct current deviation; adjusting and controlling the smaller value in the receiving end direct current deviation and the receiving end direct current voltage deviation to obtain a modulation voltage direct current component; performing voltage outer loop and current inner loop control to obtain a double-closed-loop control component; wherein the voltage outer loop control is capacitor voltage balance control of a receiving end VSC sub-module so as to obtain a reference value of active current inner loop control in the current inner loop control; performing circulating current suppression control to obtain a circulating current suppression component; and generating a control signal of the receiving end VSC according to the modulation voltage direct current component, the double closed-loop control component and the circulating current suppression component to control the receiving end VSC.

Description

Technical Field

[0001] The present invention belongs to the technical field of HVDC transmission, and particularly relates to a receiving-end VSC of a hybrid HVDC transmission, a control method thereof, and a computer device. Background Art

[0002] In the prior art, a schematic diagram of a monopole connection of a common UHV hybrid HVDC transmission system is as Figure 1 shown. The figure shows the connection relationship of the upper bridge arm, and the connection relationship and control mode of the lower bridge arm are the same as those of the upper bridge arm. The sending end is a line-commutated converter (LCC) or a multi-source adaptive line-commutated converter (SLCC), and the receiving end is a voltage-source converter (VSC). LCC and SLCC have the advantages of strong overcurrent capacity and low cost, but there is a risk of commutation failure; VSC adopts a modular multilevel converter topology composed of full half-bridge hybrid sub-modules, and has the advantages of no commutation failure risk, active and reactive decoupled control, etc., but the investment cost is high. The hybrid HVDC transmission system composed of LCC / SLCC and VSC can improve the stability of the AC-DC system and has economic advantages at the same time, and is a transmission method with broad engineering application prospects.

[0003] Among them, the sending-end LCC / SLCC adopts a constant DC current control mode, and the receiving-end VSC adopts a constant DC voltage control under normal conditions and a constant DC current control during faults. Its controller structure is as Figure 2 shown. Under steady-state conditions, the receiving-end VSC valve group is in a DC voltage control mode, and the receiving-end DC voltage is subjected to voltage inner-loop control and current outer-loop control to obtain a double-loop control component. The output result of the DC voltage controller is always U dcref / 2, that is, the DC voltage modulation component U dcmod of the receiving-end VSC = U dcref / 2. Using the DC component U dcmod of the modulation voltage of the receiving-end VSC minus the double-loop control component U1, and then subtracting the circulating current suppression component U1 output by the circulating current suppressor to obtain a parameter of the valve controller. Using the DC component U dcmod of the modulation voltage of the receiving-end VSC plus the double-loop control component U1, and then subtracting the circulating current suppression component U2 output by the circulating current suppressor to obtain another parameter of the valve controller. The valve controller generates trigger pulses according to the two input parameters to achieve the active power balance of the hybrid HVDC transmission system. The DC current controller and the sub-module capacitor voltage balance controller are enabled during the DC line fault crossing to clear the short-circuit current of the VSC. During the sending-end AC system fault, the receiving-end pole control obtains the AC voltage amplitude of the sending end through inter-station communication. According to the degree of AC voltage drop, the DC voltage command value of the VSC valve group is reduced, or through the enable signals I dcen and U dcenSwitch to the DC current control mode to suppress the 100Hz overvoltage on the DC side caused by asymmetric faults and shorten the fault recovery time.

[0004] Since, in this control mode, an enable signal needs to be obtained from the control terminal through inter-station communication to perform mode switching so as to achieve fault ride-through. If there is an inter-station communication delay, it will cause the switching between the DC voltage control mode and the DC current control mode to be not timely enough, thus affecting the fault ride-through of the receiving-end VSC. Summary of the Invention

[0005] The object of the present invention is to provide a receiving-end VSC of a hybrid HVDC transmission, its control method, and a computer device, so as to solve the technical problem that the inter-station communication delay causes the switching between the DC voltage control mode and the DC current control mode to be not timely enough, thus affecting the fault ride-through of the receiving-end VSC.

[0006] To solve the above technical problem, the present invention provides a control method for a receiving-end VSC of a hybrid HVDC transmission, including the following steps:

[0007] Calculate the difference between the reference value of the receiving-end DC voltage and the actually sampled value of the receiving-end DC voltage to obtain the deviation of the receiving-end DC voltage; calculate the difference between the actually sampled value of the receiving-end DC current and the reference value of the receiving-end DC current to obtain the deviation of the receiving-end DC current; adjust and control the smaller value among the deviation of the receiving-end DC current and the deviation of the receiving-end DC voltage to obtain the DC component of the modulation voltage;

[0008] Perform voltage outer loop and current inner loop control to obtain double closed-loop control components; among them, the voltage outer loop control is the capacitor voltage balance control of the receiving-end VSC sub-module to obtain the reference value of the active current inner loop control in the current inner loop control;

[0009] Perform circulating current suppression control to obtain circulating current suppression components;

[0010] Generate a control signal for the receiving-end VSC according to the DC component of the modulation voltage, the double closed-loop control components, and the circulating current suppression components, and use the generated control signal to control the receiving-end VSC.

[0011] Further, the calculation method of the DC current reference value is: calculate the smaller value between the output of the low-voltage current limiting module and the preset receiving-end DC current command value, and the result obtained by subtracting the DC current margin from the smaller value is the DC current reference value;

[0012] When the receiving-end DC pole voltage is greater than or equal to the upper limit of the set range, the output of the low-voltage current limiting module is the preset receiving-end DC current command value; when the receiving-end DC pole voltage is less than or equal to the upper limit of the set range and greater than or equal to the lower limit of the set range, the output of the low-voltage current limiting module is positively correlated with the receiving-end DC pole voltage; when the receiving-end DC pole voltage is less than or equal to the lower limit of the set range, the output of the low-voltage current limiting module is equal to the set current, and the set current is less than the receiving-end DC current command value.

[0013] Further, calculate the calculation result of subtracting the actually measured receiving-end DC current value from the preset receiving-end DC current command value, and calculate the product of the calculation result and the set multiple, where the set multiple is greater than 0 and less than 1; use the preset receiving-end DC voltage command value plus the receiving-end DC voltage margin, and then subtract the product to obtain the receiving-end DC voltage reference value.

[0014] Further, the receiving-end DC voltage reference value is equal to the preset receiving-end DC voltage command value plus the receiving-end DC voltage margin.

[0015] Further, when the output of the low-voltage current limiting module starts to decrease from the receiving-end DC current reference value, the DC current margin switches from the first set value to the second set value; when the output of the low-voltage current limiting module rises to the receiving-end DC current reference value, the DC current margin switches from the second set value to the first set value; the second set value is greater than the first set value.

[0016] Further, the method for switching the DC current margin is that the first set value or the second set value is switched to the second set value and the first set value respectively through a first-order inertia link.

[0017] Further, calculate the calculation result of subtracting the actually measured receiving-end DC current value from the preset receiving-end DC current command value, and calculate the product of the calculation result and the set multiple, where the set multiple is greater than 0 and less than 1; use the preset receiving-end DC voltage command value plus the receiving-end DC voltage margin, and then subtract the product to obtain the receiving-end DC voltage reference value; the receiving-end DC current margin is equal to zero, and the receiving-end DC voltage margin is greater than zero.

[0018] Further, the DC component of the modulation voltage is the limited modulation voltage DC component. The maximum value of the limited modulation voltage DC component is half of the maximum value of the receiving-end VSC DC voltage, and the minimum value of the limited modulation voltage DC component is half of the minimum value of the receiving-end VSC DC voltage.

[0019] The present invention is an improved invention, and its beneficial effects are as follows: By using the adjusted value of the smaller one between the receiving-end DC current deviation and the receiving-end DC voltage deviation as the DC component of the modulation voltage of the receiving-end VSC, when an AC fault occurs at the sending end, the actual measured value of the receiving-end DC current decreases, and the receiving-end DC current deviation decreases. When it decreases to be less than the receiving-end DC voltage deviation, it automatically switches to the DC current closed-loop control mode, realizing the automatic switching between the DC current closed-loop control mode and the DC voltage closed-loop control mode. There is no need to obtain an enabling signal from a higher level for mode switching, without relying on the mode switching enabling signal sent by the control end, and not affected by the inter-station communication delay. At the same time, the output of the sub-module capacitor voltage controller is used as the active current command value to control the active power balance of the VSC valve group, realizing the stability of the sub-module capacitor voltage, and jointly controlling the current and voltage of the VSC to the reference value with the DC voltage modulation component of the receiving-end VSC.

[0020] To solve the above technical problems, the present invention also provides a computer device, including a processor, and the processor implements the method steps of the hybrid DC transmission receiving-end VSC control method of the present invention when executing a computer program.

[0021] The present invention is an improved invention, and its beneficial effects are the same as those of the hybrid DC transmission receiving-end VSC control method of the present invention.

[0022] To solve the above technical problems, the present invention also provides a hybrid DC transmission receiving-end VSC, including a VSC controller, and the VSC controller includes a processor, and the processor implements the method steps of the hybrid DC transmission receiving-end VSC control method of the present invention when executing a computer program.

[0023] The present invention is an improved invention, and its beneficial effects are the same as those of the hybrid DC transmission receiving-end VSC control method of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a schematic diagram of the single-pole connection of the UHV hybrid DC transmission system in the background technology of the present invention;

[0025] Figure 2 is the controller structure diagram of the receiving-end VSC in the background technology of the present invention;

[0026] Figure 3 is the controller structure diagram of the receiving-end VSC in the embodiment of the hybrid DC transmission receiving-end VSC control method of the present invention;

[0027] Figure 4 is the structure diagram of the DC current margin controller in the embodiment of the hybrid DC transmission receiving-end VSC control method of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0028] A receiving - end VSC of a hybrid HVDC transmission system, its control method, and a computer device according to the present invention, by taking the adjustment value of the smaller value among the receiving - end DC current deviation and the receiving - end DC voltage deviation as the DC component of the modulation voltage of the receiving - end VSC. When an AC fault occurs at the sending end, the actually measured value of the receiving - end DC current decreases, and the receiving - end DC current deviation decreases. When it decreases to be less than the receiving - end DC voltage deviation, it automatically switches to the DC current closed - loop control mode, realizing the automatic switching between the DC current closed - loop control mode and the DC voltage closed - loop control mode. There is no need to obtain an enabling signal from a higher - level for mode switching, does not rely on a mode - switching enabling signal sent by a control end, is not affected by the inter - station communication delay, and at the same time uses the output of the sub - module capacitor voltage controller as the active current command value to control the active power balance of the VSC valve group, realizing the stability of the sub - module capacitor voltage, and jointly with the DC voltage modulation component of the receiving - end VSC, controlling the current and voltage of the VSC to the reference value.

[0029] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the drawings and embodiments.

[0030] Embodiment of the control method for the receiving - end VSC of hybrid HVDC transmission:

[0031] The single - pole wiring schematic diagram of the UHV hybrid HVDC transmission system of the present invention is as Figure 1 shown. The sending end is a line - commutated converter (LCC) or a multi - source adaptive line - commutated converter (SLCC), and the receiving end is a voltage - source converter (VSC). In order to control the receiving - end VSC to achieve fault ride - through and not rely on reliable and fast inter - station communication, the present invention proposes the following method.

[0032] The VSC valve group control method of the present invention includes the following steps: calculating the difference between the receiving - end DC voltage reference value and the actually measured value U of the receiving - end DC voltage dcGi to obtain the receiving - end DC voltage deviation; calculating the difference between the actually measured value I of the receiving - end DC current dc and the receiving - end DC current reference value to obtain the receiving - end DC current deviation; adjusting and controlling the smaller value among the receiving - end DC current deviation and the receiving - end DC voltage deviation to obtain the DC component U of the modulation voltage of the receiving - end VSC dcmod ; performing voltage outer - loop and current inner - loop control to obtain double - closed - loop control components, where the voltage outer - loop control is the sub - module capacitor voltage balance control of the receiving - end VSC; performing circulating - current suppression control to obtain a circulating - current suppression component; generating a control signal for the receiving - end VSC according to the DC component of the modulation voltage of the receiving - end VSC, the double - closed - loop control components, and the circulating - current suppression component.

[0033] In this embodiment, the receiving - end DC current reference value is equal to the receiving - end DC current margin I marg and the preset receiving - end DC current command value Idcref and the difference from the smaller value in the output of the low-voltage current limiting module. When the receiving-end DC pole voltage U dcP is greater than or equal to the upper limit of the set range, the output of the low-voltage current limiting module is the preset receiving-end DC current command value; when the receiving-end DC pole voltage U dcP is less than the upper limit of the set range, the output of the low-voltage current limiting module is the receiving-end DC pole voltage. The size of the DC current reference value can be reduced through the output of the low-voltage current limiting module, which does not depend on the DC current command value and can avoid the impact of inter-station communication delay on the fault crossing performance.

[0034] As an optimal implementation mode, in this embodiment, the receiving-end DC voltage reference value is equal to the preset receiving-end DC voltage command value U dcref plus the DC voltage margin U marg , and then subtract the preset receiving-end DC current command value I dcref and the set multiple k of the difference between the actual measured value I dc of the receiving-end DC current. It can make the switching between the DC current closed-loop control mode and the DC voltage closed-loop control mode smoother. As other implementation modes, the DC voltage reference value can directly be equal to the DC voltage command value plus the DC voltage margin.

[0035] The control block diagram of the VSC valve group control method of the present invention is as Figure 3 shown. The DC component U dcmod of the VSC valve group modulation voltage is determined by the output of the DC voltage-current closed-loop controller. The DC voltage-current closed-loop controller includes a DC voltage closed-loop controller and a DC current closed-loop controller. The DC voltage closed-loop controller and the DC current closed-loop controller share a regulator for adjustment and control. In this embodiment, the regulator is selected as a PI regulator, which adjusts the smaller value of the DC voltage deviation and the DC current deviation and then outputs, and this output is the output of the DC voltage-current closed-loop controller. The receiving-end DC current deviation is equal to the receiving-end DC current I dc minus the difference between the smaller value between the output of the low-voltage current limiting module VDCL and the DC current command value I dcref and the DC current margin I marg ; it can be expressed by the formula: I dc -[min(I dcref , VDCL)-I marg , where VDCL is the output of the low-voltage current limiting module, and the maximum output value of the low-voltage current limiting module is equal to the DC voltage command value. When the receiving-end DC pole voltage U dcP is within the set range, the output increases as the receiving-end DC pole voltage U dcP increases. When the receiving-end DC pole voltage U dcP is greater than the upper limit of the set range, it no longer increases and is constantly the output corresponding to the upper limit of the set range. When the receiving-end DC pole voltage UdcP When it is less than the lower limit of the set range, it is always the output corresponding to the lower limit of the set range. The DC voltage deviation at the receiving end is equal to the DC voltage command value U dcref plus the DC voltage margin U marg , minus the sampled value U of the valve group DC voltage dcGi , and then minus the DC current command value I dcref minus the receiving-end DC current I dc The product of the difference and the set multiple k. It can be expressed by the formula: U dcref +U marg -U dcGi -k*(I dcref -I dc ), the set multiple is greater than 0 and less than 1. In this embodiment, the set multiple k = 0.1. The result of PI regulation needs to be limited. Its maximum value is U dcmax / 2, and the minimum value is U dcmin / 2, U dcmax is the maximum limit value of the DC voltage, and U dcmin is the minimum limit value of the DC voltage.

[0036] When the receiving-end DC pole voltage is less than the upper limit of the set range, the output of the low-voltage current limiting module is positively correlated with the receiving-end DC pole voltage. In this embodiment, the positive correlation is a proportional relationship, and the set range is [0.3 pu, 0.8 pu]. When the receiving-end DC pole voltage is greater than or equal to the upper limit of the set range, the output of the low-voltage current limiting module VDCL is the DC current command value I dcref . When the receiving-end DC pole voltage is less than or equal to the lower limit of the set range, the output of the low-voltage current limiting module VDCL is the set current. The lower limit value of the low-voltage current limiting module is under a serious fault of the sending-end AC system (generally referring to the AC voltage being lower than 0.6 times the rated value). On the premise of meeting the electrical stress safety of the converter, according to the principle of minimizing the transmission power loss as much as possible, the set current is set through simulation. In this embodiment, the set current is 0.345 pu.

[0037] The active current command value is equal to the output of the sub-module capacitor voltage controller, which controls the active power balance of the VSC valve group and realizes the stability of the sub-module capacitor voltage. Under the combined action of the DC voltage closed-loop control and the sub-module capacitor voltage control, the DC voltage of the VSC valve group is controlled to the target value.

[0038] When VDCL acts, the DC current margin I marg is adjusted from the first set value I set1 to the second set value I set2 . The second set value I set2 > the first set value I set1 , in this embodiment, the first set value I set1 = 0.1, and the second set value Iset2 A controlled by a DC current margin controller with a DC current margin of 0.5. The structure of the DC current margin controller is as Figure 4 shown, and the inputs are the first set value I set1 or the second set value I set2 . Before the VDCL operates, the input is the first set value I set1 . After the VDCL operates, the input is the second set value I set2 ; the outputs are 0 and the DC current margin I marg . When a fault occurs in the DC line, the output is 0. When the DC line has no fault, the output is the adjusted value of the first set value or the second set value, that is, the DC current margin I marg ; there is an inertia link between the input and output of the DC current margin controller. The inertia link can smooth the change of the input and then adjust the output correspondingly when the input changes each time, making the change of the DC current margin smoother.

[0039] Since the sending - end LCC is in a constant DC current control mode, the DC current command value I dcref is equal to the DC current measurement value I dc , and the DC current deviation is equal to the DC current margin I marg which is equal to 0.1. When the DC voltage deviation is less than the DC current deviation, the DC component U dcmod of the VSC valve - group modulation voltage is the result after PI regulation of the DC voltage closed - loop control output value. At this time, the number of sub - modules put into operation in one phase unit of the VSC valve - group is determined by the DC voltage closed - loop controller. The sub - module capacitor voltage controller adjusts the active current of the VSC valve - group to control the active power balance of the VSC valve - group and achieve the stability of the sub - module capacitor voltage. Under the combined action of the DC voltage closed - loop control and the sub - module capacitor voltage control, the DC voltage of the VSC valve - group is controlled to the reference value.

[0040] When a fault occurs in the sending - end AC system, the receiving - end DC current decreases and the DC current deviation decreases. When the DC current deviation is less than the DC voltage deviation, the DC component of the VSC valve - group modulation voltage becomes the output value of the DC current closed - loop control. At this time, due to the decrease of the DC current and the reduction of the DC current deviation, the DC component U dcmod of the VSC valve - group modulation voltage decreases. Therefore, the number of sub - modules put into operation in the VSC valve - group phase unit decreases, making the DC voltage of the VSC valve - group decrease, which is beneficial to suppressing the DC 100Hz over - voltage caused by the asymmetric fault of the sending - end AC system. After the DC voltage of the VSC valve - group decreases, the receiving - end DC pole voltage U dcP decreases. At this time, the receiving - end low - voltage current - limiting module VDCL operates and its output decreases. When the output of the VDCL is lower than the current DC current command value, the receiving - end DC current is reduced to prevent the DC current from over - charging when the fault is cleared.

[0041] When the receiving-end low-voltage current limiting module VDCL operates, the output of the DC current margin controller smoothly increases from the first set value of 0.1 to the second set value of 0.5 after passing through a first-order inertia link. The switching control of the DC current margin enables the receiving end to be in a constant DC voltage control mode at the moment when the sending-end AC fault is cleared, quickly controlling the DC voltage to the target value. At the same time, when the current recovers to a relatively high level, through the action of the low-voltage current limiting module VDCL and the DC current margin controller, the DC current deviation is increased, and it is switched to the constant DC voltage control mode for a short time. At this time, the receiving-end voltage is lower than the sending-end voltage, which helps to accelerate the recovery of the receiving-end current and improve the power recovery rate.

[0042] In this embodiment, the output of the DC voltage margin controller can be switched between the adjusted value and the third set value (set to 0 in this embodiment). Therefore, during the DC line fault, the DC current margin is switched to 0, the DC voltage margin is switched to 0.1, and the DC current command value is switched to the third set value of 0, so that the VSC valve bank is in a constant DC current control mode to clear the short-circuit current of the VSC valve bank. After the deionization ends, the DC current margin is switched to I set2 , the DC voltage margin is switched to 0, and the VSC valve bank resumes in a constant DC voltage control mode, quickly controlling the DC voltage to the target value. The third set value is a relatively small value, which can quickly adjust the receiving-end DC current to the DC current command value in the DC current closed-loop control mode. During the DC line fault, the preset receiving-end DC voltage margin U marg is greater than 0, and is set to 0.1 in this embodiment.

[0043] Embodiment of computer device:

[0044] A computer device of the present invention includes a processor, and the processor implements the steps of the method as described in the embodiment of the VSC control method for the receiving end of the hybrid DC transmission of the present invention when executing a computer program. The specific process, principle, and beneficial effects of this method have been described in detail in the method embodiment, and will not be repeated in this embodiment.

[0045] Among them, the processor can be a microprocessor MCU, a digital signal processor DSP, a programmable logic device FPGA, and other processing devices.

[0046] Embodiment of the receiving-end VSC of hybrid DC transmission:

[0047] A receiving-end VSC of the hybrid DC transmission of the present invention includes a VSC controller, and the VSC controller includes a processor. The processor implements the steps of the method as described in the embodiment of the VSC control method for the receiving end of the hybrid DC transmission of the present invention when executing a computer program. The specific process, principle, and beneficial effects of this method have been described in detail in the method embodiment, and will not be repeated in this embodiment.

[0048] Among them, the processor can be a processing device such as a microprocessor MCU, a digital signal processor DSP, or a field-programmable gate array FPGA.

[0049] In summary, for a receiving-end VSC of a hybrid HVDC transmission, its control method, and a computer device according to the present invention, the automatic switching between a DC voltage closed-loop control module and a DC current closed-loop control mode is achieved by adjusting the smaller value of the DC voltage deviation and the DC current deviation, without going through a higher-level control signal and without relying on timely and reliable inter-station communication. As long as a sending-end AC fault occurs, it can automatically switch to the DC current closed-loop control mode to suppress the overvoltage of the receiving-end DC. Further, when a sending-end AC fault occurs in the present invention, the output of the low-voltage current limiting module is used to replace the DC current command value, and the DC current command value does not need to change during the whole process, solving the problem that the update of the DC current command value is not timely due to the delay of the inter-station communication, which affects the fault ride-through effect.

[0050] Further, the present invention increases the DC voltage deviation at the receiving end by using the output result of the low-voltage current limiting module to replace the DC current command value and increasing the output of the DC current margin controller, so as to automatically switch to the DC voltage closed-loop control mode at the end of the fault, quickly restore the DC power, and accelerate the speed of fault ride-through.

[0051] Further, the output result of the DC current margin controller of the present invention can be switched between a first set value, a second set value, and a third set value. When a DC line fault occurs, the output automatically switches to the third set value, and the third set value is a smaller value, which can quickly adjust the receiving-end DC current to the command value in the DC current closed-loop control mode.

[0052] Further, when calculating the DC voltage deviation, the present invention also considers the product of a set multiple and the difference between the DC current command value and the receiving-end DC current, which can make the switching between the DC current closed-loop control mode and the DC voltage closed-loop control mode more flexible.

Claims

1. A hybrid DC transmission receiving end VSC control method, characterized in that: The following steps are involved: Calculate the difference between the DC voltage reference value at the receiving end and the DC voltage actual value at the receiving end to obtain the DC voltage deviation at the receiving end; The difference between the actual DC current value at the receiving end and the DC current reference value at the receiving end is calculated to obtain the DC current deviation at the receiving end; the smaller value of the DC current deviation at the receiving end and the DC voltage deviation at the receiving end is adjusted and controlled to obtain the DC component of the modulation voltage; Perform voltage outer loop and current inner loop control to obtain double closed loop control components; The voltage outer loop control is to control the capacitor voltage balance of the receiving end VSC submodule to obtain the reference value of the active current inner loop control in the current inner loop control; Performing circulation suppression control to obtain a circulation suppression component; A control signal of the receiving-end VSC is generated according to the modulation voltage DC component, the dual closed-loop control component and the circulating current suppression component, and the receiving-end VSC is controlled by using the generated control signal.

2. The hybrid DC transmission receiving-end VSC control method according to claim 1, characterized in that: The DC current reference value is calculated by: calculating the smaller value between the output of the low-voltage current limiting module and the preset receiving-end DC current command value, and the result obtained by subtracting the DC current margin from the smaller value is the DC current reference value; When the DC pole voltage at the receiving end is greater than or equal to the upper limit of the set range, the output of the low-voltage current limiting module is the preset DC current command value at the receiving end; When the DC pole voltage at the receiving end is less than or equal to the upper limit of the set range and greater than or equal to the lower limit of the set range, the output of the low-voltage current limiting module is positively correlated with the DC pole voltage at the receiving end; when the DC pole voltage at the receiving end is less than or equal to the lower limit of the set range, the output of the low-voltage current limiting module is equal to the set current, and the set current is less than the DC current command value at the receiving end.

3. The hybrid DC transmission receiving-end VSC control method according to claim 1, characterized in that: Calculate the result of subtracting the actual value of the DC current at the receiving end from the preset receiving end DC current command value, and calculate the product of the calculation result and a set multiple, where the set multiple is greater than 0 and less than 1; use the preset receiving end DC voltage command value plus the receiving end DC voltage margin, and then subtract the product to obtain the receiving end DC voltage reference value.

4. The hybrid DC transmission receiving-end VSC control method according to claim 1, characterized in that: The receiving-end DC voltage reference value is equal to a preset receiving-end DC voltage command value plus a receiving-end DC voltage margin.

5. The hybrid DC transmission receiving-end VSC control method according to claim 2, characterized in that: When the output of the low-voltage current limiting module starts to decrease from the receiving end DC current reference value, the DC current margin switches from the first set value to the second set value; when the output of the low-voltage current limiting module rises to the receiving end DC current reference value, the DC current margin switches from the second set value to the first set value; the second set value is greater than the first set value.

6. The hybrid DC transmission receiving-end VSC control method according to claim 5, characterized in that: The method for switching the DC current margin is that the first setting value or the second setting value switches to the second setting value or the first setting value accordingly through a first-order inertia link.

7. The hybrid DC transmission receiving-end VSC control method according to claim 2, characterized in that: Calculate the result of subtracting the actual value of the DC current at the receiving end from the preset receiving end DC current command value, and calculate the product of the calculation result and the set multiple, where the set multiple is greater than 0 and less than 1; use the preset receiving end DC voltage command value plus the receiving end DC voltage margin, and then subtract the product to obtain the receiving end DC voltage reference value; the receiving end DC current margin is equal to zero, and the receiving end DC voltage margin is greater than zero.

8. The hybrid DC transmission receiving-end VSC control method according to any one of claims 1 to 6, characterized in that: The modulation voltage DC component is the modulation voltage DC component after amplitude limiting, the maximum value of the modulation voltage DC component after amplitude limiting is half of the maximum value of the receiving end VSC DC voltage, and the minimum value of the modulation voltage DC component after amplitude limiting is half of the minimum value of the receiving end VSC DC voltage.

9. A computer device comprising a processor, characterized in that: The processor implements the steps of the hybrid DC transmission receiving-end VSC control method as described in any one of claims 1 to 8 when executing the computer program.

10. A hybrid DC transmission receiving-end VSC, comprising a VSC controller, the VSC controller comprising a processor, characterized in that: The processor implements the steps of the hybrid DC transmission receiving-end VSC control method as described in any one of claims 1 to 8 when executing the computer program.

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