A coordinated configuration method and system for a converter valve submodule and a bypass switch

Abstract

The present invention discloses a method and system for collaborative configuration of converter valve submodules and bypass switches, relating to the field of flexible direct current transmission technology. A bypass circuit is obtained by connecting a bypass switch in series with a reactor unit; the reactor unit includes a series inductor and a resistor; a bypass circuit is connected to both ends of each submodule in the converter valve to obtain a collaborative circuit; a transient analysis model of a submodule in the converter valve is established; multi-objective constraints are applied to the transient analysis model based on the operating conditions of the converter valve, and the transient analysis model is solved to obtain first selection parameters for the reactor unit; capacitor discharge conditions and bypass switch misclosing conditions are simulated to obtain second selection parameters for the reactor unit; and the second selection parameters are used to configure the collaborative circuit of the submodules in the converter valve. By using the embodiments of the present invention, the closing current of the bypass switch can be effectively reduced, and the rate of rise of the short-circuit current when the bypass switch is misclosed can be effectively reduced, thereby improving the protection success rate.

Description

Technical Field

[0001] The present invention relates to the technical field of flexible direct current transmission technology, and in particular to a method and system for collaboratively configuring a converter valve submodule and a bypass switch. Background Art

[0002] Flexible DC transmission boasts controllability, flexibility, and stability, and is the future development direction for long-distance, high-capacity DC transmission. It holds broad prospects for distributed generation, island power generation, and urban expansion. The MMC converter valve is a key component in a flexible DC transmission system, converting AC voltage to DC voltage and vice versa. It consists of multiple submodules connected in series, each containing power electronic devices such as IGBTs and designed with a bypass function. When a submodule fault is detected, a high-speed bypass switch activates, short-circuiting the submodule and preventing the fault's impact from spreading to the entire system.

[0003] Mistakenly closing a bypass switch and excessive electrodynamic forces after closing, preventing it from carrying current for a long time, are serious problems. They can cause equipment damage, system instability, and even safety incidents. Traditional protection measures often struggle to achieve both a high success rate and low discharge current after a false closing. Summary of the Invention

[0004] The technical problem to be solved by the present invention is how to improve the effectiveness of traditional bypass switches in protecting submodules, and provide a method and system for the coordinated configuration of converter valve submodules and bypass switches, which can effectively reduce the closing circuit of the bypass switch and effectively reduce the short-circuit current rising rate when the bypass switch is mistakenly closed, thereby improving the protection success rate.

[0005] To solve the above technical problems, an embodiment of the present invention provides a method for collaboratively configuring a converter valve submodule and a bypass switch, comprising:

[0006] Connecting the bypass switch in series with the reactor unit to obtain a bypass circuit; the reactor unit includes an inductor and a resistor connected in series;

[0007] Both ends of each submodule in the converter valve are connected to a bypass circuit to obtain a coordinated circuit; the submodules include a full-bridge submodule and a half-bridge submodule;

[0008] Establishing a transient analysis model of a submodule in the converter valve;

[0009] Performing multi-objective constraints on the transient analysis model according to the operating conditions of the converter valve, and solving the transient analysis model to obtain first selection parameters of the reactor unit;

[0010] According to the first selection parameters, simulating a capacitor discharge condition and a bypass switch misclosing condition in the transient analysis model to obtain second selection parameters for the reactor unit;

[0011] The second selection parameters are used to configure the coordinated circuit of the submodules in the converter valve.

[0012] As an improvement to the above solution, the step of establishing a transient analysis model of a submodule in the converter valve includes:

[0013] Simulating a preset fault type of the converter valve to obtain a fault discharge path including a submodule in the converter valve;

[0014] Obtaining a main discharge circuit of the submodule according to the fault discharge path;

[0015] According to the main discharge circuit, the submodules in the converter valve are equivalent to RLC series circuits to establish a transient analysis model.

[0016] As an improvement to the above solution, the method of performing multi-objective constraints on the transient analysis model according to the operating conditions of the converter valve and solving the transient analysis model to obtain the first selection parameters of the reactor unit includes:

[0017] Obtaining an initial selection parameter range for the reactor unit based on physical and engineering constraints of the reactor unit;

[0018] obtaining a first objective function of the transient analysis model according to a first operating condition when the capacitor is discharged after the bypass switch in the converter valve is closed;

[0019] Obtaining a second objective function of the transient analysis model according to a second operating condition of the converter valve submodule during a fault or fault recovery process;

[0020] Obtaining a third objective function of the transient analysis model according to a third operating condition in which the reactor unit generates losses;

[0021] Setting constraints of the transient analysis model according to the first objective function, the second objective function, and the third objective function;

[0022] The transient analysis model is solved according to the constraint conditions to select a plurality of first selection parameters within the initial selection parameter range of the reactor unit.

[0023] As an improvement to the above solution, setting the constraint conditions of the transient analysis model according to the first objective function, the second objective function, and the third objective function includes:

[0024] According to the first objective function, setting a first constraint condition of the transient analysis model, wherein the first constraint condition is a peak current constraint of the capacitor;

[0025] According to the second objective function, setting a second constraint condition of the transient analysis model, wherein the second constraint condition is at least one of a current fluctuation constraint and a voltage fluctuation constraint of the submodule;

[0026] According to the third objective function, a third constraint condition of the transient analysis model is set, where the third constraint condition is at least one of an occupied space constraint and a control loss constraint.

[0027] As an improvement to the above solution, the transient analysis model is obtained by equivalently forming an RLC series circuit. Then, according to the constraint conditions, the transient analysis model is solved to select a plurality of first selection parameters within the initial selection parameter range of the reactor unit, including:

[0028] Obtaining a differential equation of the transient analysis model according to a discharge process of the RLC series circuit in the time domain;

[0029] According to the initial selection parameter range, setting the initial conditions of the difference equation;

[0030] According to the principle of exponential decay oscillation or overdamped decay oscillation, a damping coefficient of the transient analysis model is obtained;

[0031] According to the constraint conditions and the damping coefficient, an intelligent algorithm is used to iteratively solve the transient analysis model to obtain a plurality of first selection parameters, where the first selection parameters satisfy the initial selection parameter range.

[0032] As an improvement to the above solution, according to the first selection parameter, simulating the capacitor discharge condition and the bypass switch misclosing condition in the transient analysis model to obtain the second selection parameter of the reactor unit includes:

[0033] updating the configuration of the transient analysis model according to the first selection parameter;

[0034] Simulating, in the updated transient analysis model, a fourth operating condition in which the capacitor of the converter valve submodule is discharged through the bypass switch, and obtaining a peak current as a first verification result;

[0035] Performing a closing verification on the coordinated circuit in the updated transient analysis model to obtain a second verification result; the closing verification simulates a fifth operating condition when the bypass switch is mistakenly closed;

[0036] The first selection parameters are optimized according to the first verification result and the second verification result to obtain second selection parameters.

[0037] As an improvement to the above solution, simulating the fourth operating condition when the capacitor of the converter valve submodule is discharged through the bypass switch in the updated transient analysis model to obtain the peak current as the first verification result includes:

[0038] charging the submodule according to the highest voltage of the capacitor in the submodule and exiting the short-circuit protection function of the IGBT in the submodule;

[0039] sending a control signal to the bypass switch and one of the IGBTs to simulate a fourth operating condition in which the capacitor in the submodule is discharged through the bypass switch;

[0040] A first verification result is obtained based on the reliability of closing the bypass switch under the fourth working condition.

[0041] As an improvement to the above solution, performing closing verification on the coordinated circuit in the updated transient analysis model to obtain a second verification result includes:

[0042] Charging the submodule and enabling the IGBT short-circuit protection function in the submodule;

[0043] sending a control signal to the bypass switch and one of the IGBTs to simulate a fifth operating condition in which the bypass switch is mistakenly closed when the IGBT in the submodule is turned on;

[0044] A second verification result is obtained according to the short-circuit current rising rate of the IGBT under the fifth operating condition.

[0045] As an improvement to the above solution, optimizing the first selection parameter according to the first verification result and the second verification result to obtain the second selection parameter includes:

[0046] If the first verification result is that the actual current peak value under the fourth operating condition is greater than the preset limit current value, then obtaining the inductance improvement value of the inductor according to the square of the ratio of the actual current peak value to the limit current value as the optimization parameter of the reactor unit;

[0047] If the second verification result is that the false closing protection fails under the fifth working condition, obtaining an actual peak current and a current rise rate, and obtaining a resistance increase value and a power increase value of the resistor according to the actual peak current and the current rise rate as optimization parameters of the reactor unit;

[0048] The first selection parameter is optimized according to the optimization parameter to obtain the second selection parameter.

[0049] An embodiment of the present invention further provides a coordinated configuration system of a converter valve submodule and a bypass switch, comprising:

[0050] An element series setting module is used to connect the bypass switch and the reactor unit in series to obtain a bypass circuit; the reactor unit includes an inductor and a resistor connected in series;

[0051] A component parallel setting module is used to connect a bypass circuit at both ends of each submodule in the converter valve to obtain a coordinated circuit; the submodules include a full-bridge submodule and a half-bridge submodule;

[0052] A model building module, used to build a transient analysis model of a submodule in the converter valve;

[0053] a model solving module, configured to perform multi-objective constraints on the transient analysis model according to the operating conditions of the converter valve, and solve the transient analysis model to obtain first selection parameters of the reactor unit;

[0054] a model simulation module, configured to simulate a capacitor discharge condition and a bypass switch misclosing condition in the transient analysis model according to the first selection parameters, to obtain second selection parameters for the reactor unit;

[0055] A circuit configuration module is used to configure the coordinated circuit of the submodules in the converter valve using the second selection parameters.

[0056] Compared with the prior art, the present invention discloses a method and system for collaborative configuration of converter valve submodules and bypass switches. The method comprises connecting a bypass switch in series with a reactor unit to form a bypass circuit; the reactor unit comprises a series inductor and a resistor; a bypass circuit is connected to both ends of each submodule in the converter valve to form a collaborative circuit; the submodule comprises a full-bridge submodule and a half-bridge submodule; a transient analysis model is established for a submodule in the converter valve; multi-objective constraints are applied to the transient analysis model based on the operating conditions of the converter valve, and the transient analysis model is solved to obtain first selection parameters for the reactor unit; based on the first selection parameters, capacitor discharge conditions and bypass switch mis-closing conditions are simulated in the transient analysis model to obtain second selection parameters for the reactor unit; and the second selection parameters are used to configure the collaborative circuit of the submodules in the converter valve. The embodiments of the present invention can effectively reduce the closing current of the bypass switch, effectively reduce the rate of rise of the short-circuit current when the bypass switch is mis-closed, and improve the protection success rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 1 is a schematic flow chart of steps of a method for coordinating configuration of a converter valve submodule and a bypass switch provided by an embodiment of the present invention;

[0058] Figure 2 1 is a circuit diagram of a half-bridge submodule in a converter valve connected to the bypass circuit, provided by an embodiment of the present invention;

[0059] Figure 3 1 is a circuit diagram of a full-bridge submodule in a converter valve connected to the bypass circuit, provided by an embodiment of the present invention;

[0060] Figure 4 is a timing diagram of a control signal provided by an embodiment of the present invention;

[0061] Figure 5 The diagram is a structural diagram of a coordinated configuration system of a converter valve submodule and a bypass switch provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0062] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0063] In the description of the specification and claims, it should be understood that the terms "first," "second," etc., are used solely for descriptive purposes to distinguish between identical technical features and are not to be construed as indicating or implying relative importance or implicitly specifying the number of technical features being referred to, nor do they necessarily describe a sequential or chronological order. The terms are interchangeable where appropriate. Thus, a feature specified as "first" or "second" may explicitly or implicitly include at least one of those features.

[0064] Bypass switches play a key role in flexible DC transmission systems, ensuring that when a submodule fails, it is quickly isolated to prevent the fault from further expanding and affecting the operation of the entire system.

[0065] When the system is operating normally, due to a fault in the bypass switch itself, the bypass switch may be mistakenly closed. At this time, the short-circuit protection function of the IGBT may not be able to operate in time to complete the protection of the IGBT. In addition, in certain faults, closing the bypass switch to bypass the sub-module may cause the capacitor energy to be released through the bypass switch, and a large electric force may act on the bypass switch, causing it to fail to close normally or the impedance after closing is high and unable to pass current for a long time, keeping the sub-module in a short-circuit state.

[0066] Inadvertent closing of the bypass switch and excessive electric force after closing that prevents long-term current flow are serious problems that may cause equipment damage, system instability and even safety accidents.

[0067] Based on the above considerations, an embodiment of the present invention provides a method for coordinating the configuration of a converter valve submodule and a bypass switch. Figure 1 In this embodiment, the coordinated configuration method of the converter valve submodule and the bypass switch is specifically performed through steps S1 to S6:

[0068] S1. Connecting a bypass switch and a reactor unit in series to obtain a bypass circuit; the reactor unit includes an inductor and a resistor connected in series;

[0069] S2. Connecting the bypass circuit to both ends of each submodule in the converter valve to obtain a coordinated circuit; the submodules include a full-bridge submodule and a half-bridge submodule;

[0070] S3. Establishing a transient analysis model of a submodule in the converter valve;

[0071] S4. Performing multi-objective constraints on the transient analysis model according to the operating conditions of the converter valve, and solving the transient analysis model to obtain first selection parameters of the reactor unit;

[0072] S5. Based on the first selection parameters, simulate a capacitor discharge condition and a bypass switch misclosing condition in the transient analysis model to obtain second selection parameters for the reactor unit;

[0073] S6. Use the second selection parameters to configure the coordinated circuit of the submodules in the converter valve.

[0074] It should be noted that in step S2, the bypass circuit can be applied to the configuration of the full-bridge sub-module or the half-bridge sub-module, which can effectively reduce the closing current of the original bypass switch in the sub-module, and effectively reduce the short-circuit current rise rate when the bypass switch in the sub-module is mistakenly closed, thereby improving the protection success rate.

[0075] In practical applications, the bypass circuit may be configured for each submodule of the MMC converter valve, or may be configured for only some submodules. The specific circuit topology setting should be determined according to actual grid requirements.

[0076] For example, see Figure 2 and Figure 3 In the embodiment of the present invention, the IGBT element is identified by T. Figure 2 In the figure, the two ends of the half-bridge submodule are at the collector and emitter of the IGBT element T2, and the bypass circuit formed by connecting the bypass switch and the reactor unit in series, that is, the dotted box part in the figure, is connected to the collector and emitter of T2 to form a collaborative circuit. Figure 3In the embodiment, the two ends of the full-bridge submodule are at the collector of T4 and the emitter of T2 respectively, and the bypass circuit is connected between the collector of T4 and the emitter of T2 to form a cooperative circuit.

[0077] It should be noted that the bypass circuit obtained by connecting the bypass switch and the reactor unit in series is configured at both ends of the submodule, so that the reactor unit only takes effect when the bypass switch is mistakenly closed and the capacitor energy is released through the bypass switch. When the submodule operates normally, the system current does not flow through the reactor unit, and the system operation mode is the same as when the reactor unit is not configured and does not change.

[0078] The reactor unit can suppress the current rise rate when the bypass switch is mistakenly closed and the capacitor energy is released through the bypass switch through the series inductance and capacitance. After suppressing the current rise rate, the success probability of the IGBT short-circuit protection can be improved when the bypass switch is mistakenly closed. At the same time, the current peak when the capacitor energy is released through the bypass switch can also be reduced, thereby reducing the electric force that the bypass switch bears under extreme fault conditions and improving the reliability of long-term current flow after extreme faults.

[0079] As a preferred embodiment, step S3, establishing a transient analysis model of a submodule in the converter valve, includes:

[0080] Simulating a preset fault type of the converter valve to obtain a fault discharge path including a submodule in the converter valve;

[0081] Obtaining a main discharge circuit of the submodule according to the fault discharge path;

[0082] According to the main discharge circuit, the submodules in the converter valve are equivalent to RLC series circuits to establish a transient analysis model.

[0083] It should be noted that, because current flows through the bypass switch and the coordinated circuit when the bypass switch is closed or the converter valve fails, the main discharge circuit includes at least the coordinated circuit or an equivalent circuit to the coordinated circuit. In a preferred embodiment of the present invention, it is not necessary to perform equivalence on the submodule circuits of the entire converter valve; instead, at least the main discharge circuit is evaluated.

[0084] In some preferred embodiments, the main discharge circuit includes a coordinated circuit. The transient analysis model established after circuit equivalence includes R, L, and C, where R is the equivalent series resistance of the submodules in the converter valve, L is the inductance of the reactor unit in the coordinated circuit, and C is the capacitance of the capacitors in the submodules in the converter valve. Furthermore, the equivalent series circuit includes reactor unit losses, capacitor equivalent series resistance, and contact resistance of wires and switches.

[0085] As a preferred embodiment, step S4, performing multi-objective constraints on the transient analysis model according to the operating conditions of the converter valve, and solving the transient analysis model to obtain the first selection parameters of the reactor unit, is specifically performed through steps S41-S46:

[0086] S41. Obtain an initial selection parameter range of the reactor unit based on physical and engineering constraints of the reactor unit.

[0087] It should be noted that the initial selection parameter range is preliminarily selected based on the component structure size, insulation performance and heat dissipation capacity. In some preferred embodiments, the initial selection parameter range includes a set of impedance ranges [ , ], , Z is the overall impedance of the reactor unit. In other preferred embodiments, the initial selection parameter range includes a set of resistance ranges and a set of inductance ranges, which respectively constrain the resistance and inductance value ranges in the reactor unit.

[0088] S42. Obtain a first objective function of the transient analysis model according to a first operating condition when the capacitor is discharged after the bypass switch in the converter valve is closed.

[0089] It should also be noted that the first operating condition corresponds to the operating condition in which the converter valve discharges through the cooperative circuit under normal circumstances. By simulating the first operating condition to generate the first objective function, the discharge condition of the bypass switch can be obtained, which is closely related to the parameter selection of the reactor unit.

[0090] S43. Obtain a second objective function of the transient analysis model according to a second operating condition of the converter valve submodule during a fault or fault recovery process.

[0091] The second operating condition corresponds to a bypass switch failure in the converter valve submodule and the inability to discharge normally through the coordinated circuit during fault recovery. Increasing the reactance value will cause changes in the dynamic response characteristics of the submodule or valve arm voltage and AC side current. Especially during transient processes such as fault removal or fault recovery, a larger inductance value will slow the current change rate, but it will also cause system regulation lag. Generating a second objective function based on the second operating condition can minimize the degradation of the system's dynamic indicators, such as regulation time and overshoot, and ensure that voltage fluctuations are within the set threshold.

[0092] S44. Obtain a third objective function of the transient analysis model according to a third operating condition in which the reactor unit generates losses.

[0093] The third operating condition simulates the operating condition where the reactor unit itself has copper loss and iron loss. The greater the inductance of the reactor unit and the larger the space it occupies, the greater the impedance loss. By simulating the third operating condition to generate the third objective function, the loss and volume can be reduced while meeting the protection requirements.

[0094] S45. Set constraints of the transient analysis model according to the first objective function, the second objective function, and the third objective function.

[0095] S46. Solve the transient analysis model according to the constraint conditions to select a plurality of first selection parameters within the initial selection parameter range of the reactor unit.

[0096] Further, preferably, step S45, setting the constraint conditions of the transient analysis model according to the first objective function, the second objective function and the third objective function, includes:

[0097] According to the first objective function, setting a first constraint condition of the transient analysis model, wherein the first constraint condition is a peak current constraint of the capacitor;

[0098] According to the second objective function, setting a second constraint condition of the transient analysis model, wherein the second constraint condition is at least one of a current fluctuation constraint and a voltage fluctuation constraint of the submodule;

[0099] According to the third objective function, a third constraint condition of the transient analysis model is set, where the third constraint condition is at least one of an occupied space constraint and a control loss constraint.

[0100] It should be noted that the peak current constraint of the capacitor in the first constraint condition is correlated with the maximum peak current allowed by the bypass switch. The second constraint condition is the rated limit of the system level for voltage and current fluctuations of the MMC valve arm or submodule.

[0101] In some preferred embodiments, according to the first objective function The second objective function And the third objective function , establish a multi-objective function ,in, 、 and is a preset weight coefficient. The weight coefficient can be determined according to the actual design priority. In other preferred embodiments, the objective function is processed by using a Pareto frontier method without explicitly assigning weights.

[0102] For example, taking the establishment of a multi-objective function for selecting inductance parameters in a reactor unit as an example, the multi-objective function is ,in, is the peak current when the switch is closed and discharged, is the deviation of the system voltage waveform during a fault or fault recovery. The loss is the reactor loss and / or the additional loss in the system due to the reactor.

[0103] Preferably, the transient analysis model is obtained by equivalently connecting an RLC series circuit. Step S46, solving the transient analysis model according to the constraint conditions to select a plurality of first selection parameters within the initial selection parameter range of the reactor unit, includes:

[0104] Obtaining a differential equation of the transient analysis model according to a discharge process of the RLC series circuit in the time domain;

[0105] According to the initial selection parameter range, setting the initial conditions of the difference equation;

[0106] According to the principle of exponential decay oscillation or overdamped decay oscillation, a damping coefficient of the transient analysis model is obtained;

[0107] According to the constraint conditions and the damping coefficient, an intelligent algorithm is used to iteratively solve the transient analysis model to obtain a plurality of first selection parameters, where the first selection parameters satisfy the initial selection parameter range.

[0108] For example, the differential equation of the transient analysis model is ,in, is the inductor current value in the transient analysis model at time t. Furthermore, the capacitor voltage can usually be used In some preferred embodiments, only the inductor current i(t) is concerned, and the capacitor voltage Recorded as , is the capacitor voltage at the initial time t=0. Furthermore, in some preferred embodiments, ignoring linear factors, the differential equation is expressed as ,and , , that is, assuming that the inductor current starts from 0 at the moment of discharge.

[0109] It should be noted that, in the case of damping (R>0), the general solution of the second-order system can be an exponential decay oscillation or overdamped decay. Recorded as ,when When , the system is underdamped and the discharge current may oscillate; when When , the system is in a critical state; when When , the system is overdamped and no oscillation occurs.

[0110] In some preferred embodiments, the intelligent algorithm is a genetic algorithm, a particle swarm optimization algorithm, an ant colony algorithm, a simulated annealing algorithm, or a hybrid algorithm. The intelligent algorithm iteratively updates the selection parameters within the initial selection parameter range, gradually approaching the optimal solution. After convergence, at least one set of first selection parameters and their corresponding performance indicators are obtained, providing a reference for actual selection.

[0111] It should be noted that when the intelligent algorithm is used to update the selection parameters in the initial selection parameter range, the initial parameters need to be selected in advance. For example, by L=C / (I m / U m ) 2 Calculate the initial parameters of the inductor by R=P / I arm 2 Calculate the initial parameters of the resistor.

[0112] In the above scheme, by limiting the peak current of the capacitor discharging through the bypass switch as the limiting target, limiting the peak current to be less than the tolerable value of the bypass switch, preliminarily selecting the initial parameters of the reactor unit, and verifying and adjusting them based on the initial parameters.

[0113] As a preferred embodiment, step S5, based on the first selection parameters, simulates the capacitor discharge condition and the bypass switch misclosing condition in the transient analysis model to obtain the second selection parameters of the reactor unit, which is specifically performed by steps S51-S54:

[0114] S51. Update the configuration of the transient analysis model according to the first selection parameter;

[0115] S52. Simulating, in the updated transient analysis model, a fourth operating condition in which the capacitor of the converter valve submodule is discharged through the bypass switch, and obtaining a peak current as a first verification result;

[0116] S53, performing a closing verification on the coordinated circuit in the updated transient analysis model to obtain a second verification result; the closing verification is to simulate a fifth operating condition when the bypass switch is mistakenly closed;

[0117] S54: Optimize the first selection parameter according to the first verification result and the second verification result to obtain a second selection parameter.

[0118] In the above scheme, by simulating the fourth and fifth working conditions, the situations of incorrect closing of the bypass switch and excessive electric force after closing making it unable to pass current for a long time can be analyzed, and the effectiveness of the connection of the reactor unit can also be verified.

[0119] Furthermore, preferably, step S52, simulating the fourth operating condition when the capacitor of the converter valve submodule is discharged through the bypass switch in the updated transient analysis model to obtain a peak current as the first verification result, includes:

[0120] charging the submodule according to the highest voltage of the capacitor in the submodule and exiting the short-circuit protection function of the IGBT in the submodule;

[0121] sending a control signal to the bypass switch and one of the IGBTs to simulate a fourth operating condition in which the capacitor in the submodule is discharged through the bypass switch;

[0122] A first verification result is obtained based on the reliability of closing the bypass switch under the fourth working condition.

[0123] In the above scheme, the sub-module capacitor voltage is first charged to the maximum voltage of the sub-module, the short-circuit protection of the IGBT is exited, the bypass switch is closed, and the working condition in which the capacitor discharges through the bypass switch is created. Then, it is observed whether the bypass switch can be reliably closed to obtain the reliability of the bypass switch closing, and then the first verification result is obtained.

[0124] Preferably, step S53, performing closing verification on the cooperative circuit in the updated transient analysis model to obtain a second verification result, includes:

[0125] Charging the submodule and enabling the IGBT short-circuit protection function in the submodule;

[0126] sending a control signal to the bypass switch and one of the IGBTs to simulate a fifth operating condition in which the bypass switch is mistakenly closed when the IGBT in the submodule is turned on;

[0127] A second verification result is obtained according to the short-circuit current rising rate of the IGBT under the fifth operating condition.

[0128] In the above scheme, the sub-module capacitor voltage is charged to the maximum operating voltage of the sub-module unlocked state, the IGBT short-circuit protection is enabled, and the bypass switch is closed to simulate the fifth operating condition. The short-circuit current rise rate of the IGBT is used to observe whether the IGBT short-circuit protection can be successfully protected to obtain the second verification result.

[0129] Furthermore, as a preferred embodiment, the control signal in step S52 or S53 includes a first control signal for controlling the bypass switch and a second control signal for controlling the IGBT in the submodule; wherein:

[0130] The first control signal is converted from a low level signal to a high level signal at a first moment, and is converted from a high level signal to a low level signal at a second moment; the time difference between the second moment and the first moment is a first adjustable pulse width;

[0131] The second control signal is converted from a low-level signal to a high-level signal at a third moment, and is converted from a high-level signal to a low-level signal at a fourth moment; the third moment is obtained by delaying the second moment by a preset delay time; the time difference between the fourth moment and the third moment is the first adjustable pulse width.

[0132] For example, see Figure 4 The S1 control signal is a first control signal for controlling the bypass switch; the T1 control signal is a second control signal for controlling the IGBT in the submodule; and the preset delay time is 1500 μs. In this embodiment of the present invention, the bypass switch is closed for at least 3500 μs between the first moment and the fourth moment.

[0133] Preferably, step S54, optimizing the first selection parameter according to the first verification result and the second verification result to obtain the second selection parameter, includes:

[0134] If the first verification result is that the actual current peak value under the fourth operating condition is greater than the preset limit current value, then obtaining the inductance improvement value of the inductor according to the square of the ratio of the actual current peak value to the limit current value as the optimization parameter of the reactor unit;

[0135] If the second verification result is that the false closing protection fails under the fifth working condition, obtaining an actual peak current and a current rise rate, and obtaining a resistance increase value and a power increase value of the resistor according to the actual peak current and the current rise rate as optimization parameters of the reactor unit;

[0136] The first selection parameter is optimized according to the optimization parameter to obtain the second selection parameter.

[0137] In some preferred embodiments, the current limit is the tolerable limit of the bypass switch. When the actual current peak under the first operating condition exceeds the preset current limit, the inductance is further increased by a factor proportional to the square of the ratio of the measured actual current peak to the maximum tolerable current. In the second operating condition, if the bypass switch false closing protection fails, consideration is given to increasing the resistance to further reduce the peak current and current rise rate when the bypass switch is falsely closed. Following the principle of matching power and resistance, the resistance is increased by 5% and the power is increased by 5%.

[0138] In the above scheme, the reactor unit is formed by the series combination of inductance and resistance, which not only reduces the closing current of the bypass switch, but also accelerates the decay rate of the current, so that the energy borne by each component is smaller and the protection effect is more obvious. In addition, by establishing a transient analysis model and simulating the capacitor discharge condition and the bypass switch misclosing condition, the selection parameters of the reactor unit can be set efficiently and accurately, and the generated selection parameters meet the system constraints and performance requirements. The collaborative configuration method of the converter valve submodule and the bypass switch provided by the embodiment of the present invention can effectively reduce the closing current of the bypass switch, effectively reduce the short-circuit current rise rate when the bypass switch is misclosed, and improve the protection success rate.

[0139] The embodiment of the present invention provides a coordinated configuration system of a converter valve submodule and a bypass switch. Figure 5 The coordinated configuration system of the converter valve submodule and the bypass switch includes an element series setting module 11, an element parallel setting module 12, a model building module 13, a model solving module 14, a model simulation module 15 and a circuit configuration module 16, wherein:

[0140] An element series setting module 11 is used to connect the bypass switch and the reactor unit in series to obtain a bypass circuit; the reactor unit includes an inductor and a resistor connected in series;

[0141] The component parallel setting module 12 is used to connect the bypass circuit at both ends of each submodule in the converter valve to obtain a coordinated circuit; the submodules include a full-bridge submodule and a half-bridge submodule;

[0142] A model building module 13, configured to build a transient analysis model of a submodule in the converter valve;

[0143] a model solving module 14, configured to perform multi-objective constraints on the transient analysis model according to the operating conditions of the converter valve, and solve the transient analysis model to obtain first selection parameters of the reactor unit;

[0144] a model simulation module 15 for simulating a capacitor discharge condition and a bypass switch misclosing condition in the transient analysis model according to the first selection parameters to obtain second selection parameters for the reactor unit;

[0145] The circuit configuration module 16 is configured to configure the coordinated circuit of the submodules in the converter valve using the second selection parameters.

[0146] As a preferred embodiment, the model building module 13 is specifically used to:

[0147] Simulating a preset fault type of the converter valve to obtain a fault discharge path including a submodule in the converter valve;

[0148] Obtaining a main discharge circuit of the submodule according to the fault discharge path;

[0149] According to the main discharge circuit, the submodules in the converter valve are equivalent to RLC series circuits to establish a transient analysis model.

[0150] As a preferred embodiment, the model solving module 14 includes:

[0151] an initial range acquisition unit, configured to obtain an initial selection parameter range of the reactor unit according to physical and engineering constraints of the reactor unit;

[0152] a first objective function establishing unit, configured to obtain a first objective function of the transient analysis model according to a first operating condition when the capacitor is discharged after the bypass switch in the converter valve is closed;

[0153] a second objective function establishing unit, configured to obtain a second objective function of the transient analysis model according to a second operating condition of the converter valve submodule during a fault or fault recovery process;

[0154] a third objective function establishing unit, configured to obtain a third objective function of the transient analysis model according to a third operating condition in which the reactor unit generates losses;

[0155] a constraint condition setting unit, configured to set the constraint conditions of the transient analysis model according to the first objective function, the second objective function, and the third objective function;

[0156] The first selection parameter selection unit is used to solve the transient analysis model according to the constraint conditions to select a plurality of first selection parameters within the initial selection parameter range of the reactor unit.

[0157] Furthermore, preferably, the constraint condition establishing unit is specifically configured to:

[0158] According to the first objective function, setting a first constraint condition of the transient analysis model, wherein the first constraint condition is a peak current constraint of the capacitor;

[0159] According to the second objective function, setting a second constraint condition of the transient analysis model, wherein the second constraint condition is at least one of a current fluctuation constraint and a voltage fluctuation constraint of the submodule;

[0160] According to the third objective function, a third constraint condition of the transient analysis model is set, where the third constraint condition is at least one of an occupied space constraint and a control loss constraint.

[0161] Preferably, the first selection parameter selection unit is specifically used to:

[0162] Obtaining a differential equation of the transient analysis model according to a discharge process of the RLC series circuit in the time domain;

[0163] According to the initial selection parameter range, setting the initial conditions of the difference equation;

[0164] According to the principle of exponential decay oscillation or overdamped decay oscillation, a damping coefficient of the transient analysis model is obtained;

[0165] According to the constraint conditions and the damping coefficient, an intelligent algorithm is used to iteratively solve the transient analysis model to obtain a plurality of first selection parameters, where the first selection parameters satisfy the initial selection parameter range.

[0166] As a preferred embodiment, the model simulation module 15 includes:

[0167] a configuration updating unit, configured to update the configuration of the transient analysis model according to the first selection parameter;

[0168] a first verification unit, configured to simulate, in the updated transient analysis model, a fourth operating condition in which the capacitor of the converter valve submodule is discharged through the bypass switch, and obtain a peak current as a first verification result;

[0169] A second verification unit is configured to perform a closing verification on the coordinated circuit in the updated transient analysis model to obtain a second verification result; the closing verification is to simulate a fifth operating condition when the bypass switch is mistakenly closed;

[0170] A selection parameter optimization unit is used to optimize the first selection parameter according to the first verification result and the second verification result to obtain a second selection parameter.

[0171] Furthermore, preferably, the first verification unit is specifically used to:

[0172] charging the submodule according to the highest voltage of the capacitor in the submodule and exiting the short-circuit protection function of the IGBT in the submodule;

[0173] sending a control signal to the bypass switch and one of the IGBTs to simulate a fourth operating condition in which the capacitor in the submodule is discharged through the bypass switch;

[0174] A first verification result is obtained based on the reliability of closing the bypass switch under the fourth working condition.

[0175] Preferably, the second verification unit is specifically used to:

[0176] Charging the submodule and enabling the IGBT short-circuit protection function in the submodule;

[0177] sending a control signal to the bypass switch and one of the IGBTs to simulate a fifth operating condition in which the bypass switch is mistakenly closed when the IGBT in the submodule is turned on;

[0178] A second verification result is obtained according to the short-circuit current rising rate of the IGBT under the fifth operating condition.

[0179] Preferably, the selection parameter optimization unit is specifically used to:

[0180] If the first verification result is that the actual current peak value under the fourth operating condition is greater than the preset limit current value, then obtaining the inductance improvement value of the inductor according to the square of the ratio of the actual current peak value to the limit current value as the optimization parameter of the reactor unit;

[0181] If the second verification result is that the false closing protection fails under the fifth working condition, obtaining an actual peak current and a current rise rate, and obtaining a resistance increase value and a power increase value of the resistor according to the actual peak current and the current rise rate as optimization parameters of the reactor unit;

[0182] The first selection parameter is optimized according to the optimization parameter to obtain the second selection parameter.

[0183] In the above scheme, the reactor unit is formed by the series combination of inductance and resistance, which can not only reduce the closing current of the bypass switch, but also accelerate the decay rate of the current, so that the energy borne by each component is smaller and the protection effect is more obvious; in addition, by establishing a transient analysis model and simulating the capacitor discharge working condition and the bypass switch misclosing working condition, the selection parameters of the reactor unit can be set efficiently and accurately, and the generated selection parameters meet the system constraints and performance requirements. The collaborative configuration system of the converter valve submodule and the bypass switch provided by the embodiment of the present invention can effectively reduce the closing current of the bypass switch, effectively reduce the short-circuit current rise rate when the bypass switch is misclosed, and improve the protection success rate.

[0184] Those skilled in the art will appreciate that all or part of the processes in the above-described method embodiments can be implemented by instructing the relevant hardware through a computer program. The program can be stored in a computer-readable storage medium, and when executed, the program can include the processes in the above-described method embodiments. The storage medium can be a magnetic disk, an optical disk, a read-only memory (ROM), or a random access memory (RAM).

[0185] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for coordinating the configuration of a converter valve submodule and a bypass switch, characterized in that: include: Connecting the bypass switch in series with the reactor unit to obtain a bypass circuit; the reactor unit includes an inductor and a resistor connected in series; Both ends of each submodule in the converter valve are connected to a bypass circuit to obtain a coordinated circuit; the submodules include a full-bridge submodule and a half-bridge submodule; Establishing a transient analysis model of a submodule in the converter valve; Performing multi-objective constraints on the transient analysis model according to the operating conditions of the converter valve, and solving the transient analysis model to obtain first selection parameters of the reactor unit; According to the first selection parameters, simulating a capacitor discharge condition and a bypass switch misclosing condition in the transient analysis model to obtain second selection parameters for the reactor unit; configuring the coordinated circuit of the submodule in the converter valve using the second selection parameter; The step of establishing a transient analysis model of a submodule in the converter valve includes: Simulating a preset fault type of the converter valve to obtain a fault discharge path including a submodule in the converter valve; Obtaining a main discharge circuit of the submodule according to the fault discharge path; According to the main discharge circuit, the submodules in the converter valve are equivalent to RLC series circuits to establish a transient analysis model.

2. The method for coordinating the configuration of the converter valve submodule and the bypass switch according to claim 1, characterized in that: The step of subjecting the transient analysis model to multi-objective constraints according to the operating conditions of the converter valve and solving the transient analysis model to obtain the first selection parameters of the reactor unit includes: Obtaining an initial selection parameter range for the reactor unit based on physical and engineering constraints of the reactor unit; obtaining a first objective function of the transient analysis model according to a first operating condition when the capacitor is discharged after the bypass switch in the converter valve is closed; Obtaining a second objective function of the transient analysis model according to a second operating condition of the converter valve submodule during a fault or fault recovery process; Obtaining a third objective function of the transient analysis model according to a third operating condition in which the reactor unit generates losses; Setting constraints of the transient analysis model according to the first objective function, the second objective function, and the third objective function; The transient analysis model is solved according to the constraint conditions to select a plurality of first selection parameters within the initial selection parameter range of the reactor unit.

3. The method for coordinating the configuration of the converter valve submodule and the bypass switch according to claim 2, characterized in that: The setting of the constraint conditions of the transient analysis model according to the first objective function, the second objective function, and the third objective function includes: According to the first objective function, setting a first constraint condition of the transient analysis model, wherein the first constraint condition is a peak current constraint of the capacitor; According to the second objective function, setting a second constraint condition of the transient analysis model, wherein the second constraint condition is at least one of a current fluctuation constraint and a voltage fluctuation constraint of the submodule; According to the third objective function, a third constraint condition of the transient analysis model is set, where the third constraint condition is at least one of an occupied space constraint and a control loss constraint.

4. The method for coordinating the configuration of the converter valve submodule and the bypass switch according to claim 2, wherein: The transient analysis model is obtained by equivalently operating an RLC series circuit. Then, according to the constraint conditions, the transient analysis model is solved to select a plurality of first selection parameters within the initial selection parameter range of the reactor unit, including: Obtaining a differential equation of the transient analysis model according to a discharge process of the RLC series circuit in the time domain; According to the initial selection parameter range, setting the initial conditions of the difference equation; According to the principle of exponential decay oscillation or overdamped decay oscillation, a damping coefficient of the transient analysis model is obtained; According to the constraint conditions and the damping coefficient, an intelligent algorithm is used to iteratively solve the transient analysis model to obtain a plurality of first selection parameters, where the first selection parameters satisfy the initial selection parameter range.

5. The method for coordinating configuration of a converter valve submodule and a bypass switch according to claim 1, wherein: The step of simulating a capacitor discharge condition and a bypass switch mis-closing condition in the transient analysis model based on the first selection parameter to obtain a second selection parameter for the reactor unit includes: updating the configuration of the transient analysis model according to the first selection parameter; Simulating, in the updated transient analysis model, a fourth operating condition in which the capacitor of the converter valve submodule is discharged through the bypass switch, and obtaining a peak current as a first verification result; Performing a closing verification on the coordinated circuit in the updated transient analysis model to obtain a second verification result; the closing verification simulates a fifth operating condition when the bypass switch is mistakenly closed; The first selection parameters are optimized according to the first verification result and the second verification result to obtain second selection parameters.

6. The method for coordinating configuration of a converter valve submodule and a bypass switch according to claim 5, characterized in that: The step of simulating the fourth operating condition in which the capacitor of the converter valve submodule is discharged through the bypass switch in the updated transient analysis model to obtain a peak current as a first verification result includes: charging the submodule according to the highest voltage of the capacitor in the submodule and exiting the short-circuit protection function of the IGBT in the submodule; sending a control signal to the bypass switch and one of the IGBTs to simulate a fourth operating condition in which the capacitor in the submodule is discharged through the bypass switch; A first verification result is obtained based on the reliability of closing the bypass switch under the fourth working condition.

7. The method for coordinating configuration of a converter valve submodule and a bypass switch according to claim 5, characterized in that: The performing closing verification on the coordinated circuit in the updated transient analysis model to obtain a second verification result includes: Charging the submodule and enabling the IGBT short-circuit protection function in the submodule; sending a control signal to the bypass switch and one of the IGBTs to simulate a fifth operating condition in which the bypass switch is mistakenly closed when the IGBT in the submodule is turned on; A second verification result is obtained according to the short-circuit current rising rate of the IGBT under the fifth operating condition.

8. The method for coordinating configuration of a converter valve submodule and a bypass switch according to claim 5, wherein: The optimizing the first selection parameter according to the first verification result and the second verification result to obtain the second selection parameter includes: If the first verification result is that the actual current peak value under the fourth operating condition is greater than the preset limit current value, then obtaining the inductance improvement value of the inductor according to the square of the ratio of the actual current peak value to the limit current value as the optimization parameter of the reactor unit; If the second verification result is that the false closing protection fails under the fifth working condition, obtaining an actual peak current and a current rise rate, and obtaining a resistance increase value and a power increase value of the resistor according to the actual peak current and the current rise rate as optimization parameters of the reactor unit; The first selection parameter is optimized according to the optimization parameter to obtain the second selection parameter.

9. A coordinated configuration system of a converter valve submodule and a bypass switch, characterized in that: include: An element series setting module is used to connect the bypass switch and the reactor unit in series to obtain a bypass circuit; the reactor unit includes an inductor and a resistor connected in series; A component parallel setting module is used to connect a bypass circuit at both ends of each submodule in the converter valve to obtain a coordinated circuit; the submodules include a full-bridge submodule and a half-bridge submodule; A model building module, used to build a transient analysis model of a submodule in the converter valve; a model solving module, configured to perform multi-objective constraints on the transient analysis model according to the operating conditions of the converter valve, and solve the transient analysis model to obtain first selection parameters of the reactor unit; a model simulation module, configured to simulate a capacitor discharge condition and a bypass switch misclosing condition in the transient analysis model according to the first selection parameters, to obtain second selection parameters for the reactor unit; a circuit configuration module, configured to configure a coordinated circuit of the submodules in the converter valve using the second selection parameters; The model building module is specifically used to: Simulating a preset fault type of the converter valve to obtain a fault discharge path including a submodule in the converter valve; Obtaining a main discharge circuit of the submodule according to the fault discharge path; According to the main discharge circuit, the submodules in the converter valve are equivalent to RLC series circuits to establish a transient analysis model.

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