±800kV / 8GW flexible direct current transmission converter valve operation test topology and control method

Abstract

The present application relates to a kind of ±800kV / 8GW flexible direct current transmission commutating valve operating test topology and control method.The experimental topology described in the present application is composed of test product module group, branch inductance, test product valve section 1 and test product valve section 2.According to the test current reference value, the conduction and turn-off of full-bridge switching devices in the test product valve module group are controlled, generating alternating current and direct current in the test loop;The direct current component of the capacitor voltage of test product valve section 1 and test product valve section 2 is controlled to be stable, while ensuring that the capacitor voltage of test product valve section 1 and test product valve section 2 remains balanced.The test topology and control method have good stress equivalence, high flexibility in current control, and are suitable for stress testing of commutating valve under rectification and inversion conditions, while meeting the requirements of higher voltage and larger current conditions for valve section and module stress testing, facilitating practical engineering application.

Description

Technical Field

[0001] This invention relates to the field of flexible DC transmission technology, specifically to a ±800kV / 8GW flexible DC transmission converter valve operation test topology and control method. Background Technology

[0002] Flexible DC transmission is gradually developing towards high voltage and large capacity. In the ±800kV / 8GW flexible DC transmission project, the continuous current carrying capacity of the converter valve arm reaches 4500 Arms. The modular multilevel converter (MMC) is a key device in the flexible DC transmission system. It is very sensitive to voltage, current and temperature, which reduces the operational reliability of the converter valve. Before the MMC converter valve is put into operation, it needs to undergo operational tests to verify whether its design meets the actual engineering requirements and whether the function of the converter valve is complete. Therefore, selecting a suitable operational test topology in the ±800kV / 8GW flexible DC transmission project is particularly important.

[0003] Most existing converter valve operation test topologies adopt a paired test topology, which consists of one test valve section and another valve section under test, with a large inductor connected in series between the two valve sections. This topology has the following disadvantages: 1) Poor stress equivalence of the converter valve, making it impossible to simultaneously test the stress characteristics of the converter valve under rectification and inversion conditions; 2) Inflexible current control; 3) Inability to simultaneously test the stress of the valve section and the module; 4) Inapplicability to higher voltage and higher current conditions. For ±800kV / 8GW flexible DC transmission projects, where the converter valve arm current continuous current carrying capacity reaches 4500 Arms, a suitable converter valve operation test topology needs to be proposed to complete the operational testing and evaluation of the converter valve.

[0004] Given the following problems with existing converter valve operation test topologies: 1) poor stress equivalence, making it impossible to simultaneously test converter valve stress characteristics under rectification and inverter conditions; 2) inflexible current control; 3) inability to simultaneously test the stress of valve sections and modules; and 4) unsuitability for higher voltage and higher current conditions, a suitable operation test topology and control method that balances stress equivalence and control flexibility while simultaneously enabling stress testing of valve sections and modules under higher voltage and higher current conditions is crucial for evaluating converter valves in ±800kV / 8GW flexible DC transmission projects. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a test topology for ±800kV / 8GW flexible DC transmission converter valve operation. This test topology can balance stress equivalence and control flexibility, while simultaneously meeting the requirements for stress testing of valve sections and modules under higher voltage and higher current operating conditions.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A test topology for the operation of a ±800kV / 8GW flexible DC transmission converter valve, characterized in that it includes a test module group, branch inductors, test valve section 1, and test valve section 2.

[0008] Each branch of the test module group consists of several cascaded full bridges, and each full bridge consists of two half bridge modules. The full bridge is used to test the stress characteristics of the module, and the test module group simultaneously generates the test loop current.

[0009] Each of the above branches is connected in series with a branch inductor: one end of each branch inductor is connected to the test module group, and the other end is connected to the test valve section 2;

[0010] Both test valve section 1 and test valve section 2 are composed of several cascaded half-bridge modules. One end of test valve section 1 is connected to the test module group and the other end is grounded. One end of test valve section 2 is connected to the branch inductor and the other end is grounded. Test valve section 1 is used to test the valve section stress under inverter operation and test valve section 2 is used to test the valve section stress under rectifier operation.

[0011] The test module group, branch inductor, test valve section 1 and test valve section 2 together form the operating test circuit; control the AC voltage components and DC voltage components of test valve section 1 and test valve section 2, and control the voltage output of the test module group to generate the AC current components and DC current components required in the above test circuit.

[0012] Another objective of this invention is to provide a control method based on the above-described experimental topology.

[0013] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0014] A control method for a ±800kV / 8GW flexible DC transmission converter valve operation test topology, characterized in that:

[0015] The method includes a control method for the test sample module group, a control method for test sample section 1, and a control method for test sample section 2. Specifically, it involves controlling the on and off of the full-bridge switching device in the test sample valve module group according to the test current reference value to generate AC and DC currents in the test circuit; controlling the DC component of the capacitor voltage of test sample valve section 1 and test sample valve section 2 to be stable, while ensuring that the capacitor voltages of test sample valve section 1 and test sample valve section 2 remain balanced.

[0016] Based on the above scheme, the control method for the sample module group is as follows:

[0017] (1) The reference voltages of the test sample valve section 1 and the test sample valve section 2 are expressed in the form of switching functions as follows:

[0018]

[0019]

[0020] In the above two equations, M1 is the pulse modulation ratio of module 1 of the test sample valve section; M2 is the pulse modulation ratio of module 2 of the test sample valve section; δ1 is the voltage phase of module 1 of the test sample valve section.

[0021] (2) The test current is expressed as:

[0022] i = i dc +i ac (3);

[0023] In the above formula, i dc For direct current; i ac For alternating current; i ac Represented as AC active and AC reactive components:

[0024]

[0025] In the above formula, I P I represents the effective value of the active component of the alternating current. q This represents the effective value of the reactive component of the alternating current.

[0026] (3) Ignoring the equivalent resistance of the module, the relationship between the module capacitor voltage and the test current is:

[0027]

[0028]

[0029] In the above two formulas, C is the capacitance value of the module; u 1c The voltage of the module capacitor in valve section 1 of the test sample; the effective value of the active component of the AC current; u 2c The voltage of the module capacitor in valve section 2 of the test sample;

[0030] Combining the above expressions for the test section switching function, the test current, and the relationship between the module capacitor voltage and the test current, as described in (1)-(3), we obtain the state equation of the operating test circuit:

[0031]

[0032] (4) The test module group consists of d parallel branches, and the voltage loop equations for each branch are as follows:

[0033]

[0034] In the above formula, L d Let i be the inductance of the d-th branch;d R is the current in the d-th branch; d u is the equivalent series resistance of the d-th branch; hd is the output voltage of the dth branch; u1 and u2 are the output voltages of test valve section 1 and test valve section 2, respectively;

[0035] Applying the Laplace transform to the above equation, we get:

[0036] sL d i d +R d i d (s)=u hd (s)+u1(s)-u2(s) (9);

[0037] Let the transfer function of the current controller be G. i (s), the control quantity u is obtained by adjusting the controller. h (s):

[0038] u hd (s)=u2(s)-u1(s)+G i (s)(i ref (s)-i d (s)) (10);

[0039] In the above formula, i ref (s) is the current reference value; i d (s) is the current reference value of the dth branch; the current controller adopts a PIR controller to realize accurate control of the AC active and reactive components in the test current, and at the same time realize the DC current tracking without steady-state error in the test current.

[0040] From equation (7), it can be seen that in steady state, the differential term of the DC component of the capacitor voltage of the test sample valve section 2 is 0. Considering the equivalent resistance of the module, the relationship between the active component of the AC current and the DC component of the capacitor voltage of the test sample valve section 2 is as follows:

[0041]

[0042] In the above formula, u 2dc R represents the DC component of the capacitor voltage in valve section 2 of the test sample; p The equivalent resistance of the module; I is obtained through a PI controller. P This enables DC component control of the capacitor voltage in test sample valve section 2.

[0043] Based on the above scheme, the control method for the test sample valve section 1 is as follows:

[0044] The output voltage of test valve section 1 includes both AC and DC voltage components. Considering the capacitor voltage equalization control of test valve section 1, the final switching function of test valve section 1 is:

[0045] S 1n =S1-S′ 1n (12);

[0046] In the above formula, S 1n S1′ is the switching function for the nth half-bridge module of the test sample valve section 1. n The switching function correction amount superimposed for capacitor voltage equalization control;

[0047] The final switching function of the test sample valve section 1 is applied to the module switching devices through carrier phase shift modulation to control the conduction and cutoff of the switching devices, thereby controlling the voltage output of the test sample valve section 1.

[0048] The expression for the DC component of the capacitor voltage in section 1 of the test sample valve is:

[0049]

[0050] In the above formula, u 1dc The DC component of the capacitor voltage in valve section 1 of the test sample is shown. It can be seen that the DC component of valve section 1 of the test sample is related to its phase δ1. Controlling δ1 can ensure the stability of the DC component of the capacitor voltage in valve section 1 of the test sample.

[0051] Specifically, to maintain a balanced capacitor voltage across all modules of the test valve section 1, an energy distribution principle is adopted. The direction of current i and the fluctuations in the capacitor voltage of test valve section 1 influence the switching device's on / off state. The difference between the capacitor voltage of each module of test valve section 1 and its average value is calculated. This error is then processed by a proportional controller and multiplied by the current sign determination result to obtain a correction value for the switching function, S1′. n The final switching function S is obtained by subtracting S1 from S1. 1n .

[0052] Based on the above scheme, the control method for the test sample valve section 2 is as follows:

[0053] The output voltage of test valve section 2 includes both AC and DC voltage components. Considering the capacitor voltage equalization control of test valve section 2, the final switching function of test valve section 2 is:

[0054] S 2n =S2+S2′ n (14);

[0055] In the above formula, S 2n S2′ is the switching function of the nth half-bridge module in the test valve section 2. n The switching function correction amount superimposed for capacitor voltage equalization control;

[0056] The final switching function of the test sample valve section 2 is applied to the module switching devices through carrier phase shift modulation to control the conduction and cutoff of the switching devices, thereby controlling the voltage output of the test sample valve section 2.

[0057] Specifically, to maintain a balanced capacitor voltage across all modules of test valve section 2, an energy equalization approach is adopted. The direction of current i and the fluctuations in capacitor voltage across test valve section 2 influence the switching device's on / off state. The difference between the capacitor voltage of each module in test valve section 2 and its average value is calculated. This error is then processed by a proportional controller and multiplied by the current sign determination result to obtain a correction value for the switching function, S2′. n The final switching function S obtained by adding S2 is 2n .

[0058] The ±800kV / 8GW flexible DC transmission converter valve operation test topology and control method described in this invention have the following advantages:

[0059] The test circuit current is generated by controlling the test module group. This current generation control method does not rely on inductors and is more flexible. Test valve section 1 and test valve section 2 test the stress characteristics of the converter valve under rectification and inversion conditions. The stress equivalence is better, and it can also meet the stress test requirements of valve section and module under higher voltage and higher current operating conditions, which is convenient for practical engineering applications. Attached Figure Description

[0060] The present invention includes the following figures:

[0061] Figure 1 This is the operational test topology for the flexible DC transmission converter valve of the present invention;

[0062] Figure 2 This invention provides a control strategy for the pilot sample module group in the test topology of the converter valve operation test.

[0063] Figure 3 This invention provides the control strategy for valve section 1 of the test specimen in the converter valve operation test topology.

[0064] Figure 4 The control strategy for test valve section 2 of the converter valve operation test topology of the present invention. Detailed Implementation

[0065] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0066] like Figure 1 As shown, a test topology for the operation of a ±800kV / 8GW flexible DC transmission converter valve includes a test module group, a branch inductor, a test valve section 1, and a test valve section 2.

[0067] Each branch of the test module group consists of several full-bridge cascaded modules, and each full-bridge consists of two half-bridge modules, which are used to test the stress characteristics of the module. The test module group also generates test loop current.

[0068] The branch inductors are connected in series in each branch, with one end connected to the sample module group and the other end connected to the sample valve section 2;

[0069] Both test valve section 1 and test valve section 2 are composed of several cascaded half-bridge modules. One end of test valve section 1 is connected to the test module group, and the other end is grounded. One end of test valve section 2 is connected to the branch inductor, and the other end is grounded. Test valve section 1 can be used to test the valve section stress under inverter operation, and test valve section 2 can be used to test the valve section stress under rectifier operation.

[0070] The test module group, branch inductor, and two test valve sections form an operating test circuit. The AC voltage components and DC voltage components of the two test valve sections are controlled, and the voltage output of the test module group is controlled to generate the AC current components and DC current components required in the test circuit.

[0071] The control method for the ±800kV / 8GW flexible DC transmission converter valve operation test topology is characterized in that the control method controls the on and off of the full-bridge switching devices in the test valve module group according to the test current reference value to generate AC current and DC current in the test circuit; controls the DC component of the capacitor voltage of test valve section 1 and test valve section 2 to be stable, while ensuring that the capacitor voltage of test valve section 1 and test valve section 2 remains balanced.

[0072] This includes the control methods for the sample module group, the control methods for sample valve section 1, and the control methods for sample valve section 2.

[0073] 1) such as Figure 2 As shown, the control method for the sample module group is as follows:

[0074] Both test valve section 1 and test valve section 2 employ carrier phase-shift modulation. Using the switching function analysis method, the reference voltages of test valve section 1 and test valve section 2 are expressed in switching function form as follows:

[0075]

[0076]

[0077] In the above formula, M1 is the pulse modulation ratio of the test sample valve section 1 module; M2 is the pulse modulation ratio of the test sample valve section 2 module; and δ1 is the voltage phase of the test sample valve section 1.

[0078] The test current is a mixed component of AC and DC superposition, expressed as:

[0079] i = i dc +i ac ;

[0080] In the above formula, i dc For direct current; i ac Let the alternating current be represented as alternating current; the alternating current is expressed in the form of alternating active and alternating reactive components, that is:

[0081]

[0082] In the above formula, I P I represents the effective value of the active component of the alternating current. q This represents the effective value of the reactive component of the alternating current.

[0083] Ignoring the equivalent resistance of the module, the relationship between the module capacitor voltage and the test current is as follows:

[0084]

[0085]

[0086] Combining the above equations, the expression for the switching function of the test sample valve section, and the expression for the test current, we can obtain the state equation for the operating test circuit:

[0087]

[0088] The following example, using a test topology module with two parallel branches, further illustrates the converter valve operation test topology control method for a ±800kV / 8GW flexible DC transmission project:

[0089] Write the voltage loop equations for each branch:

[0090]

[0091]

[0092] In the above formula, L1 is the inductance value of branch 1, L2 is the inductance value of branch 2; R1 is the equivalent series resistance of branch 1, R2 is the equivalent series resistance of branch 2; u h1 and u h2 U1 and U2 are the output voltages of branch 1 and branch 2, respectively; u1 and u2 are the output voltages of test valve section 1 and test valve section 2, respectively.

[0093] Applying the Laplace transform to the above equation, we get:

[0094] sL1i1+R1i1(s)=u h1 (s)+u1(s)-u2(s);

[0095] sL2i2+R2i2(s)=u h2 (s)+u1(s)-u2(s);

[0096] Let the transfer function of the current controller be G. i (s), the control quantity u is obtained by adjusting the controller. h (s):

[0097] u h1 (s)=u2(s)-u1(s)+G i (s)(i ref (s)-i1(s));

[0098] u h2 (s)=u2(s)-u1(s)+G i (s)(i ref (s)-i2(s));

[0099] In the above formula, i ref i(s) is the current reference value; i1(s) and i2(s) are the current reference values ​​of branch 1 and branch 2, respectively; the current controller adopts a PIR controller to realize the accurate control of the AC active and reactive components in the test current, and at the same time realize the DC current tracking without steady-state error in the test current.

[0100] From the state equation of the test circuit, it can be seen that in steady state, the differential term of the DC component of the voltage of the capacitor in test valve section 2 is 0. Considering the equivalent resistance of the module, the relationship between the active component of the AC current and the DC component of the voltage of the capacitor in test valve section 2 is as follows:

[0101]

[0102] In the above formula, u 2dc R represents the DC component of the capacitor voltage in valve section 2 of the test sample; p The equivalent resistance of the module; the control quantity I is obtained through a PI controller. P This enables DC component control of the capacitor voltage in test sample valve section 2.

[0103] 2) such as Figure 3 As shown, the control method for the test sample valve section 1 is as follows:

[0104] The output voltage of test valve section 1 includes both AC and DC voltage components. Without considering capacitor voltage equalization control of test valve section 1, the reference voltage of test valve section 1 is expressed as a switching function:

[0105]

[0106] From the operating state equation of the test circuit, it can be seen that the differential term of the DC component of the voltage of the capacitor in section 1 of the test sample in steady state is 0. Considering the equivalent resistance of the module, the expression for the DC component of the voltage of the capacitor in section 1 of the test sample is:

[0107]

[0108] In the above formula, u 1dc Let be the DC component of the capacitor voltage of test sample valve section 1. As can be seen from the above formula, the DC component of test sample valve section 1 is related to its phase δ1. Controlling δ1 can ensure the stability of the DC component of the capacitor voltage of test sample valve section 1.

[0109] The final switching function of the sample valve section 1 is:

[0110] S 1n =S1-S1′ n

[0111] S 1n S1′ is the switching function for the nth half-bridge module of the test sample valve section 1. n This is the correction amount of the switching function superimposed on the capacitor voltage equalization control.

[0112] To maintain a balanced capacitor voltage across all modules of test valve section 1, an energy-equalization approach is adopted. The direction of current i and the fluctuations in capacitor voltage across test valve section 1 influence the switching device's on / off states. The difference between the capacitor voltage of each module in test valve section 1 and its average value is calculated. This error is then processed by a proportional controller and multiplied by the current sign determination result to obtain a correction value S1′ for the switching function. n The final switching function obtained by subtracting from S1 is applied to the module switching devices through carrier phase shift modulation to control the switching devices to turn on and off, thereby controlling the voltage output of the test sample valve section 1.

[0113] 3) such as Figure 4 As shown, the control method for the sample valve section 2 is as follows:

[0114] The output voltage of test valve section 2 includes both AC and DC voltage components. Without considering capacitor voltage equalization control of test valve section 2, the reference voltage of test valve section 2 is expressed as a switching function:

[0115]

[0116] The final switching function of the sample valve section 2 is:

[0117] S 2n =S2+S2′ n

[0118] S 2nS2′ is the switching function of the nth half-bridge module in the test valve section 2. n This is the correction amount of the switching function superimposed on the capacitor voltage equalization control.

[0119] To maintain a balanced capacitor voltage across all modules of test valve section 2, an energy-equalization approach is adopted. The direction of current i and the fluctuations in capacitor voltage across test valve section 2 influence the switching device's on / off state. The difference between the capacitor voltage of each module in test valve section 2 and its average value is calculated. This error is then processed by a proportional controller and multiplied by the current sign determination result to obtain a correction value for the switching function, S2′. n The final switching function obtained by adding S2 is applied to the module switching devices through carrier phase shift modulation to control the switching devices to turn on and off, thereby controlling the voltage output of the test sample valve section 2.

[0120] Taking test valve 2 as an example, when the test current is in the positive direction, if the sampled capacitor voltage in test valve 2 is greater than the capacitor voltage reference value, the correction amount S2′ is... n If the value is negative, S2′ n Adding S2 to the final switching function will decrease, the capacitor charging time will shorten, the capacitor voltage will decrease, and the capacitor voltage output will be a DC voltage with a fundamental frequency ripple component. When the test current is in the negative direction, if the capacitor voltage sampled in the test valve 2 is greater than the capacitor voltage reference value, the correction amount S2′ will be... n If S2′ is positive, then S2′ n Adding S2 to the final switching function will increase the voltage, the capacitor discharge time will lengthen, the capacitor voltage will rise, and the capacitor output will be a DC voltage with a fundamental frequency ripple component. Similarly, the capacitor charging and discharging behavior when the capacitor voltage is less than the reference value can be analyzed.

[0121] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0122] The contents not described in detail in this specification are existing technologies known to those skilled in the art.

Claims

1. A control method for a ±800kV / 8GW flexible DC transmission converter valve operation test topology, characterized in that: The method includes a control method for the test sample module group, a control method for test sample valve section 1, and a control method for test sample valve section 2. Specifically, it involves controlling the on and off of the full-bridge switching devices in the test sample valve module group according to the test current reference value to generate AC and DC currents in the test circuit; controlling the DC component of the capacitor voltage of test sample valve section 1 and test sample valve section 2 to be stable, while ensuring that the capacitor voltages of test sample valve section 1 and test sample valve section 2 remain balanced. The control method for the sample module group is as follows: (1) The reference voltages of the test sample valve section 1 and the test sample valve section 2 are expressed in the form of switching functions as follows: ； ； In the above two equations, The pulse modulation ratio of module 1 of the test sample valve section; The pulse modulation ratio of module 2 in the test sample valve section; The voltage phase of valve section 1 of the test sample; (2) The test current is expressed as: ； In the above formula, It is direct current; For alternating current; Represented as AC active and AC reactive components: ； In the above formula, This represents the effective value of the active component of the alternating current. This represents the effective value of the reactive component of the alternating current. (3) Ignoring the equivalent resistance of the module, the relationship between the module capacitor voltage and the test current is as follows: ； ； In the above two equations, C The capacitance value of the module capacitor; The voltage of the module capacitor in valve section 1 of the test sample; Effective value of the active component of alternating current; The voltage of the module capacitor in valve section 2 of the test sample; Combining the above expressions for the test valve section switching function, the test current, and the relationship between the module capacitor voltage and the test current, as described in (1)-(3), we obtain the state equation of the operating test circuit: ； (4) The sample module group consists of d It consists of several parallel branches, and the voltage loop equations for each branch are as follows: ； In the above formula, For the first d The inductance of one branch; For the first d The current in each branch; For the first d The equivalent series resistance of each branch; For the first d Output voltage of the branch; and These are the output voltages of test sample valve section 1 and test sample valve section 2, respectively. Applying the Laplace transform to the above equation, we get: ； Let the transfer function of the current controller be... The control quantity is obtained by adjusting the controller. : ； In the above formula, This is the current reference value; For the first d Reference value for the current of each branch; From equation (7), it can be seen that in steady state, the differential term of the DC component of the capacitor voltage of the test sample valve section 2 is 0. Considering the equivalent resistance of the module, the relationship between the active component of the AC current and the DC component of the capacitor voltage of the test sample valve section 2 is as follows: ； In the above formula, The DC component of the capacitor voltage in valve section 2 of the test sample; The equivalent resistance of the module; obtained through a PI controller. This enables DC component control of the capacitor voltage in test sample valve section 2.

2. The control method for the ±800kV / 8GW flexible DC transmission converter valve operation test topology as described in claim 1, characterized in that: The control method for the sample valve section 1 is as follows: The output voltage of test valve section 1 includes both AC and DC voltage components. Considering the capacitor voltage equalization control of test valve section 1, the final switching function of test valve section 1 is: ； In the above formula, This is the switching function for the nth half-bridge module of the test sample valve section 1; The switching function correction amount superimposed for capacitor voltage equalization control; The final switching function of the test sample valve section 1 is applied to the module switching device through carrier phase shift modulation to control the conduction and cutoff of the switching device, thereby controlling the voltage output of the test sample valve section 1. The expression for the DC component of the capacitor voltage in section 1 of the test sample valve is: ； In the above formula, The DC component of the capacitor voltage in valve section 1 of the test sample is shown.

3. The control method for the ±800kV / 8GW flexible DC transmission converter valve operation test topology as described in claim 1, characterized in that: The control method for the sample valve section 2 is as follows: The output voltage of test valve section 2 includes both AC and DC voltage components. Considering the capacitor voltage equalization control of test valve section 2, the final switching function of test valve section 2 is: ； In the above formula, This is the switching function for the nth half-bridge module of the test sample valve section 2; The switching function correction amount superimposed for capacitor voltage equalization control; The final switching function of the test sample valve section 2 is applied to the module switching devices through carrier phase shift modulation to control the conduction and cutoff of the switching devices, thereby controlling the voltage output of the test sample valve section 2.

4. A test topology for the operation of a ±800kV / 8GW flexible DC transmission converter valve using the method described in claim 1, characterized in that, Includes the sample module group, branch inductor, sample valve section 1, and sample valve section 2: Each branch of the test module group consists of several cascaded full bridges, and each full bridge consists of two half bridge modules. The full bridge is used to test the stress characteristics of the module, and the test module group simultaneously generates the test loop current. Each of the above branches is connected in series with a branch inductor: one end of each branch inductor is connected to the test module group, and the other end is connected to the test valve section 2; Both test valve section 1 and test valve section 2 are composed of several cascaded half-bridge modules. One end of test valve section 1 is connected to the test module group and the other end is grounded. One end of test valve section 2 is connected to the branch inductor and the other end is grounded. Test valve section 1 is used to test the valve section stress under inverter operation and test valve section 2 is used to test the valve section stress under rectifier operation. The test module group, branch inductor, test valve section 1 and test valve section 2 together form the operating test circuit; control the AC voltage components and DC voltage components of test valve section 1 and test valve section 2, and control the voltage output of the test module group to generate the AC current components and DC current components required in the above test circuit.

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