Converter valve submodule and bypass switch cooperative configuration method and system

Abstract

The invention discloses a collaborative configuration method and system for a converter valve sub-module and a bypass switch, and relates to the technical field of flexible direct current transmission. The bypass switch and a reactor unit are connected in series to obtain a bypass circuit; the reactor unit comprises an inductor and a resistor which are connected in series; connecting a bypass circuit to two ends of each sub-module in the converter valve to obtain a cooperative circuit; establishing a transient analysis model of a submodule in the converter valve; performing multi-target constraint on the transient analysis model according to the operation condition of the converter valve, and solving the transient analysis model to obtain a first type selection parameter of the reactor unit; simulating a capacitor discharge working condition and a bypass switch false closing working condition to obtain a second type selection parameter of the reactor unit; and configuring a cooperative circuit of the sub-module in the converter valve by adopting the second type selection parameter. By adopting the embodiment of the invention, the closing current of the bypass switch can be effectively reduced, the rising rate of the short-circuit current when the bypass switch is mistakenly closed is effectively reduced, and the protection success rate is improved.

Description

Technical Field

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

[0002] Flexible DC transmission is controllable, flexible and stable. It is the future development direction of long-distance and large-capacity DC transmission. It has broad prospects in distributed power generation, island and urban expansion power supply. MMC converter valve is one of the key devices in the flexible DC transmission system. It is used to convert AC voltage into DC voltage or reversely convert DC voltage into AC voltage. It is composed of multiple submodules in series. Each submodule contains power electronic devices such as IGBT and is designed with bypass function. When a submodule fault is detected, the high-speed bypass switch is activated to short-circuit the submodule, thereby preventing the fault from spreading to the entire system.

[0003] The mistaken closing of the bypass switch and the excessive electric force after closing that prevents the bypass switch from flowing for a long time are serious problems, which may cause equipment damage, system instability and even safety accidents. Traditional protection measures often fail to take into account the requirements of high successful protection rate and low discharge current after mistaken 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 sub-modules, and to provide a method and system for the coordinated configuration of a converter valve sub-module and a bypass switch, which can effectively reduce the closing circuit of the bypass switch, and can also effectively reduce the short-circuit current rising rate when the bypass switch is mistakenly closed, thereby improving the protection success rate.

[0005] In order to solve the above technical problems, an embodiment of the present invention provides a method for cooperatively configuring a converter valve submodule and a bypass switch, comprising: A bypass circuit is obtained by connecting a bypass switch and a reactor unit in series; 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 submodule includes 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 the first selection parameter 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 a second selection parameter of the reactor unit; The second selection parameters are used to configure the cooperative circuit of the submodule in the converter valve.

[0006] As an improvement of the above solution, 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; According to the fault discharge path, a main discharge circuit of the submodule is obtained; According to the main discharge circuit, the submodules in the converter valve are equivalent to RLC series circuits to establish a transient analysis model.

[0007] As an improvement of 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 parameter of the reactor unit includes: According to the physical and engineering constraints of the reactor unit, an initial selection parameter range of the reactor unit is obtained; According to a first operating condition when the capacitor is discharged after the bypass switch in the converter valve is closed, a first objective function of the transient analysis model is obtained; According to a second operating condition of the submodule of the converter valve during a fault or fault recovery process, a second objective function of the transient analysis model is obtained; According to a third operating condition in which the reactor unit generates losses, a third objective function of the transient analysis model is obtained; According to the first objective function, the second objective function and the third objective function, setting the constraint conditions of the transient analysis model; 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.

[0008] As an improvement of 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: 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, and the third constraint condition is at least one of an occupied space constraint and a control loss constraint.

[0009] As an improvement of the above solution, the transient analysis model is obtained by equivalently connecting an RLC series circuit, and then 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, including: According to the discharge process of the RLC series circuit in the time domain, a differential equation of the transient analysis model is obtained; According to the initial selection parameter range, setting the initial conditions of the difference equation; According to the principle of exponential decay oscillation or over-damped 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, wherein the first selection parameters satisfy the initial selection parameter range.

[0010] As an improvement of 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: According to the first selection parameter, updating the configuration of the transient analysis model; Simulating a 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; 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 the fifth operating condition when the bypass switch is mistakenly closed; According to the first verification result and the second verification result, the first selection parameter is optimized to obtain the second selection parameter.

[0011] As an improvement of the above solution, the fourth operating condition when the capacitor of the converter valve submodule is discharged through the bypass switch is simulated in the updated transient analysis model to obtain the peak current as the first verification result, including: According to the highest voltage of the capacitor in the submodule, the submodule is charged, and the short-circuit protection function of the IGBT in the submodule is exited; 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 operating condition.

[0012] As an improvement of the above solution, performing closing verification on the cooperative 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.

[0013] As an improvement of the above solution, the first selection parameter is optimized according to the first verification result and the second verification result to obtain the second selection parameter, including: If the first verification result is that the actual current peak value under the fourth working condition is greater than the preset limit current value, then the inductance increase value of the inductor is obtained 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, then obtaining the actual peak current and the current rising rate, and obtaining the resistance value increase value and the power increase value of the resistor according to the actual peak current and the current rising rate as the optimization parameters of the reactor unit; The first selection parameter is optimized according to the optimization parameter to obtain the second selection parameter.

[0014] The embodiment of the present invention further provides a coordinated configuration system of a converter valve submodule and a bypass switch, including: 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, used for 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 parameter of the reactor unit; A model simulation module, used for simulating a capacitor discharge condition and a bypass switch misclosing condition in the transient analysis model according to the first selection parameter, to obtain a second selection parameter of the reactor unit; A circuit configuration module is used to configure the coordinated circuit of the submodules in the converter valve using the second selection parameters.

[0015] Compared with the prior art, the present invention discloses a method and system for cooperative configuration of a converter valve submodule and a bypass switch, wherein a bypass circuit is obtained by connecting a bypass switch in series with a reactor unit; the reactor unit includes an inductor and a resistor connected in series; a bypass circuit is connected at both ends of each submodule in the converter valve to obtain a cooperative circuit; the submodule includes a full-bridge submodule and a half-bridge submodule; a transient analysis model of a submodule in the converter valve is established; multi-objective constraints are imposed on the transient analysis model according to the operating conditions of the converter valve, and the transient analysis model is solved to obtain a first selection parameter of the reactor unit; according to the first selection parameter, the capacitor discharge condition and the bypass switch misclosing condition are simulated in the transient analysis model to obtain a second selection parameter of the reactor unit; the second selection parameter is used to configure the cooperative circuit of the submodule in the converter valve. By adopting the embodiment of the present invention, the closing current of the bypass switch can be effectively reduced, and the rising rate of the short-circuit current when the bypass switch is misclosed can be effectively reduced, thereby improving the protection success rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic flow chart of the steps of a method for coordinating configuration of a converter valve submodule and a bypass switch provided by an embodiment of the present invention; Figure 2 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; Figure 3 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; Figure 4 is a timing diagram of a control signal provided by an embodiment of the present invention; Figure 5 It is a structural schematic 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

[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] In the description of the specification and claims, it is to be understood that the terms first, second, etc. in the specification and claims are only used for the purpose of describing the same technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated, nor necessarily describing the order or time sequence. The terms are interchangeable where appropriate. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features.

[0019] Bypass switches play a key role in flexible DC transmission systems. They can ensure that when a submodule fails, it can be quickly isolated to prevent the fault from further expanding and affecting the operation of the entire system.

[0020] When the system is operating normally, due to the fault of the bypass switch itself, the phenomenon of mistaken closing may occur. 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, it may happen that the energy of the capacitor is released through the bypass switch, and a large electric force acts on the bypass switch, causing it to fail to close normally or the impedance is high after closing, and it cannot pass current for a long time, keeping the sub-module in a short-circuit state.

[0021] Misclosing of the bypass switch and excessive electric force after closing that prevents the bypass switch from flowing for a long time are serious problems, which may cause equipment damage, system instability and even safety accidents.

[0022] 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: S1, connecting 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; S2. Connecting the bypass circuit to both ends of each submodule in the converter valve to obtain a coordinated circuit; the submodule includes a full-bridge submodule and a half-bridge submodule; S3, establishing a transient analysis model of a submodule in the converter valve; 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 a first selection parameter of the reactor unit; S5. According to the first selection parameters, simulating a capacitor discharge condition and a bypass switch misclosing condition in the transient analysis model to obtain a second selection parameter of the reactor unit; S6. Use the second selection parameters to configure the cooperative circuit of the submodule in the converter valve.

[0023] It should be noted that in step S2, the bypass circuit can be applicable to the configuration of a full-bridge sub-module or a 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 rising rate when the bypass switch in the sub-module is mistakenly closed, thereby improving the protection success rate.

[0024] 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.

[0025] 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, respectively. 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 coordinated circuit. Figure 3 In the embodiment, the two ends of the full-bridge submodule are respectively at the collector of T4 and the emitter of T2, and the bypass circuit is connected between the collector of T4 and the emitter of T2 to form a cooperative circuit.

[0026] 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 sub-module, so that the reactor unit only works when the bypass switch is mistakenly closed and the capacitor energy is released through the bypass switch. When the sub-module operates normally, the system current does not flow through the reactor unit, and the system operation mode is the same as that without the reactor unit configured and does not change.

[0027] 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 value 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.

[0028] As a preferred implementation, step S3, 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; According to the fault discharge path, a main discharge circuit of the submodule is obtained; According to the main discharge circuit, the submodules in the converter valve are equivalent to RLC series circuits to establish a transient analysis model.

[0029] It should be noted that, since current will flow through the bypass switch and the cooperative circuit when the bypass switch is closed or the converter valve fails, the main discharge circuit at least includes the cooperative circuit or an equivalent circuit to the cooperative circuit. In a preferred embodiment of the present invention, it is not necessary to make the submodule circuit of the entire converter valve equivalent, but at least make the main discharge circuit equivalent.

[0030] In some preferred embodiments, the main discharge loop includes a coordinated circuit, and the transient analysis model established after the circuit is equivalent includes R, L and C, wherein R is the equivalent series resistance of the submodule in the converter valve, L is the inductance of the reactor unit in the coordinated circuit, and C is the capacitance of the capacitor of the submodule in the converter valve. Furthermore, the equivalent series circuit includes the loss of the reactor unit, the equivalent series resistance of the capacitor, and the contact resistance of the wire and the switch.

[0031] As a preferred implementation, step S4, multi-objective constraints are applied to the transient analysis model according to the operating conditions of the converter valve, and the transient analysis model is solved to obtain the first selection parameter of the reactor unit, which is specifically performed through steps S41-S46: S41. Obtaining an initial selection parameter range of the reactor unit according to physical and engineering constraints of the reactor unit.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] S43. Obtain a second objective function of the transient analysis model according to a second operating condition of the submodule of the converter valve during a fault or fault recovery process.

[0036] The second operating condition corresponds to the condition in which the bypass switch in the submodule of the converter valve fails and cannot be discharged normally through the cooperative circuit during the fault recovery process. Increasing the reactance value will cause the dynamic response characteristics of the submodule or valve arm voltage and the AC side current to change. Especially in transient processes such as fault removal or fault recovery, a larger inductance value will slow down the current change rate, but it will also cause system regulation lag. Generating the second objective function through the second operating condition can minimize the degradation of the system's dynamic indicators, such as adjustment time, overshoot, etc., and ensure that the voltage fluctuation is within the set threshold.

[0037] S44. Obtain a third objective function of the transient analysis model according to a third operating condition in which the reactor unit generates losses.

[0038] 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 will be. By simulating the third operating condition to generate the third objective function, the loss and volume can be reduced while meeting the protection requirements.

[0039] S45. Set constraints of the transient analysis model according to the first objective function, the second objective function and the third objective function.

[0040] 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.

[0041] 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: 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, and the third constraint condition is at least one of an occupied space constraint and a control loss constraint.

[0042] 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 voltage and current fluctuation of the MMC valve arm or submodule at the system level.

[0043] 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 priority of the actual design. In other preferred embodiments, the objective function is processed by using the Pareto frontier method without explicitly assigning weights.

[0044] 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. It is the reactor loss and / or the additional loss introduced by the reactor into the system.

[0045] 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 condition to select a plurality of first selection parameters within the initial selection parameter range of the reactor unit, includes: According to the discharge process of the RLC series circuit in the time domain, a differential equation of the transient analysis model is obtained; According to the initial selection parameter range, setting the initial conditions of the difference equation; According to the principle of exponential decay oscillation or over-damped 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, wherein the first selection parameters satisfy the initial selection parameter range.

[0046] Exemplarily, 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 and the inductor current i(t) as state variables. In some preferred embodiments, only the inductor current i(t) is considered, 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.

[0047] It should be noted that for the damped case (R>0), the general solution of the second-order system can be an exponentially decaying oscillation or an 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 , the system is overdamped and no oscillation occurs.

[0048] In some preferred embodiments, the intelligent algorithm is one of a genetic algorithm, a particle swarm optimization algorithm, an ant colony algorithm, a simulated annealing algorithm or a hybrid algorithm. The intelligent algorithm is used to iterate the selection parameters in the initial selection parameter range, gradually approaching the optimal solution, and after convergence, at least one set of first selection parameters and their corresponding performance indicators are obtained to provide a reference for actual selection.

[0049] It should be noted that when the intelligent algorithm is used to iterate the selection parameters in the initial selection parameter range, the initial parameters need to be pre-selected. m / U m ) 2 Calculate the initial parameters of the inductor by R=P / I arm 2 Calculate the initial parameters of the resistor.

[0050] In the above scheme, by limiting the peak current of the capacitor discharged 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 with the initial parameters.

[0051] As a preferred implementation, step S5, 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, is specifically performed by steps S51-S54: S51, updating the configuration of the transient analysis model according to the first selection parameter; S52, simulating a fourth operating condition in which the capacitor of the converter valve submodule is discharged through the bypass switch in the updated transient analysis model, and obtaining a peak current as a first verification result; 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 the fifth working condition when the bypass switch is mistakenly closed; S54: Optimize the first selection parameter according to the first verification result and the second verification result to obtain a second selection parameter.

[0052] In the above scheme, by simulating the fourth and fifth operating conditions, the situations of the bypass switch being mistakenly closed and the electric force being too large after closing so that it cannot flow current for a long time can be analyzed, and the access effectiveness of the reactor unit can also be verified.

[0053] Further, 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: According to the highest voltage of the capacitor in the submodule, the submodule is charged, and the short-circuit protection function of the IGBT in the submodule is exited; 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 operating condition.

[0054] In the above scheme, the submodule capacitor voltage is first charged to the maximum voltage of the submodule, 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 closing of the bypass switch, and then the first verification result is obtained.

[0055] Preferably, step S53, performing closing verification on the cooperative 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.

[0056] 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.

[0057] Furthermore, as a preferred implementation, 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: 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; 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.

[0058] For example, see Figure 4 , S1 control signal is a first control signal for controlling the bypass switch; T1 control signal is a second control signal for controlling the IGBT in the submodule; the preset delay time is 1500μs. In the embodiment of the present invention, from the first moment to the fourth moment, it is ensured that there is at least 3500μs during which the bypass switch is closed.

[0059] 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: If the first verification result is that the actual current peak value under the fourth working condition is greater than the preset limit current value, then the inductance increase value of the inductor is obtained 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, then obtaining the actual peak current and the current rising rate, and obtaining the resistance value increase value and the power increase value of the resistor according to the actual peak current and the current rising rate as the optimization parameters of the reactor unit; The first selection parameter is optimized according to the optimization parameter to obtain the second selection parameter.

[0060] In some preferred embodiments, the limit current value is the limit value that the bypass switch can tolerate. When the actual current peak value under the first working condition is greater than the preset limit current value, the inductance is further increased, and the inductance is increased in proportion to the square of the ratio of the tested actual current peak value to the maximum tolerable current. In the second working condition, if the bypass switch false closing protection fails, consider increasing the resistance to further reduce the peak current and current rise rate when the bypass switch is falsely closed. According to the principle of matching power and resistance value, the resistance value is increased by 5% and the power is increased by 5%.

[0061] 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 speed of the current, so that each component bears less energy 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, and effectively reduce the short-circuit current rise rate when the bypass switch is mistakenly closed, thereby improving the protection success rate.

[0062] 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 a component series setting module 11, a component 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: The component 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; 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 submodule includes a full-bridge submodule and a half-bridge submodule; A model building module 13, used to build a transient analysis model of a submodule in the converter valve; 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 a first selection parameter of the reactor unit; A model simulation module 15, configured to simulate a capacitor discharge condition and a bypass switch misclosing condition in the transient analysis model according to the first selection parameter, to obtain a second selection parameter of the reactor unit; The circuit configuration module 16 is used to configure the coordinated circuit of the submodules in the converter valve using the second selection parameters.

[0063] As a preferred implementation, the model building module 13 is specifically used for: Simulating a preset fault type of the converter valve to obtain a fault discharge path including a submodule in the converter valve; According to the fault discharge path, a main discharge circuit of the submodule is obtained; According to the main discharge circuit, the submodules in the converter valve are equivalent to RLC series circuits to establish a transient analysis model.

[0064] As a preferred implementation, the model solving module 14 includes: An initial range acquisition unit, used to obtain an initial selection parameter range of the reactor unit according to the physical and engineering constraints of the reactor unit; 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; 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 submodule of the converter valve during a fault or fault recovery process; 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; A constraint condition setting unit, used for setting the constraint conditions of the transient analysis model according to the first objective function, the second objective function and the third objective function; 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.

[0065] Further, preferably, the constraint condition establishing unit is specifically used to: 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, and the third constraint condition is at least one of an occupied space constraint and a control loss constraint.

[0066] Preferably, the first selection parameter selection unit is specifically used to: According to the discharge process of the RLC series circuit in the time domain, a differential equation of the transient analysis model is obtained; According to the initial selection parameter range, setting the initial conditions of the difference equation; According to the principle of exponential decay oscillation or over-damped 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, wherein the first selection parameters satisfy the initial selection parameter range.

[0067] As a preferred implementation, the model simulation module 15 includes: A configuration updating unit, configured to update the configuration of the transient analysis model according to the first selection parameter; A first verification unit is used to simulate a 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 a first verification result; A second verification unit is used to perform a closing verification on the collaborative 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; 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 the second selection parameter.

[0068] Further, preferably, the first verification unit is specifically used to: According to the highest voltage of the capacitor in the submodule, the submodule is charged, and the short-circuit protection function of the IGBT in the submodule is exited; 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 operating condition.

[0069] Preferably, the second verification unit is specifically used to: 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.

[0070] Preferably, the selection parameter optimization unit is specifically used for: If the first verification result is that the actual current peak value under the fourth working condition is greater than the preset limit current value, then the inductance increase value of the inductor is obtained 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, then obtaining the actual peak current and the current rising rate, and obtaining the resistance value increase value and the power increase value of the resistor according to the actual peak current and the current rising rate as the optimization parameters of the reactor unit; The first selection parameter is optimized according to the optimization parameter to obtain the second selection parameter.

[0071] 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 each component bears less energy 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 coordinated 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, and effectively reduce the short-circuit current rise rate when the bypass switch is mistakenly closed, thereby improving the protection success rate.

[0072] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program, and the program can be stored in a computer-readable storage medium, and when the program is executed, it can include the processes of the embodiments of the above-mentioned methods. The storage medium can be a disk, an optical disk, a read-only memory (ROM) or a random access memory (RAM), etc.

[0073] The above is a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle 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: A bypass circuit is obtained by connecting a bypass switch and a reactor unit in series; 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 submodule includes 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 the first selection parameter 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 a second selection parameter of the reactor unit; The second selection parameters are used to configure the cooperative circuit of the submodule in the converter valve.

2. A method for cooperatively configuring a converter valve submodule and a bypass switch according to claim 1, characterized in that: 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; According to the fault discharge path, a main discharge circuit of the submodule is obtained; According to the main discharge circuit, the submodules in the converter valve are equivalent to RLC series circuits to establish a transient analysis model.

3. The method for cooperatively configuring a converter valve submodule and a 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 condition of the converter valve, and solving the transient analysis model to obtain the first selection parameter of the reactor unit includes: According to the physical and engineering constraints of the reactor unit, an initial selection parameter range of the reactor unit is obtained; According to a first operating condition when the capacitor is discharged after the bypass switch in the converter valve is closed, a first objective function of the transient analysis model is obtained; According to a second operating condition of the submodule of the converter valve during a fault or fault recovery process, a second objective function of the transient analysis model is obtained; According to a third operating condition in which the reactor unit generates losses, a third objective function of the transient analysis model is obtained; According to the first objective function, the second objective function and the third objective function, setting the constraint conditions of the transient analysis model; 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.

4. A method for cooperatively configuring a converter valve submodule and a bypass switch according to claim 3, characterized in that: The step of setting the constraint conditions of the transient analysis model according to the first objective function, the second objective function and the third objective function comprises: 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, and the third constraint condition is at least one of an occupied space constraint and a control loss constraint.

5. The coordinated configuration method of a converter valve submodule and a bypass switch according to claim 3, characterized in that: The transient analysis model is obtained by equivalently connecting an RLC series circuit. Then, according to the constraint condition, solving the transient analysis model to select a plurality of first selection parameters within the initial selection parameter range of the reactor unit includes: According to the discharge process of the RLC series circuit in the time domain, a differential equation of the transient analysis model is obtained; According to the initial selection parameter range, setting the initial conditions of the difference equation; According to the principle of exponential decay oscillation or over-damped 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, wherein the first selection parameters satisfy the initial selection parameter range.

6. The method for cooperatively configuring a converter valve submodule and a bypass switch according to claim 1, characterized in that: The method of simulating a capacitor discharge condition and a bypass switch misclosing condition in the transient analysis model according to the first selection parameter to obtain a second selection parameter of the reactor unit includes: According to the first selection parameter, updating the configuration of the transient analysis model; Simulating a 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; Performing a closing verification on the cooperative circuit in the updated transient analysis model to obtain a second verification result; the closing verification is to simulate the fifth working condition when the bypass switch is mistakenly closed; According to the first verification result and the second verification result, the first selection parameter is optimized to obtain the second selection parameter.

7. A coordinated configuration method of a converter valve submodule and a bypass switch according to claim 6, characterized in that: The fourth operating condition when the capacitor of the converter valve submodule is discharged through the bypass switch is simulated in the updated transient analysis model to obtain a peak current as a first verification result, including: According to the highest voltage of the capacitor in the submodule, the submodule is charged, and the short-circuit protection function of the IGBT in the submodule is exited; 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 operating condition.

8. The method for cooperatively configuring a converter valve submodule and a bypass switch according to claim 6, characterized in that: The performing closing verification on the cooperative 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.

9. The method for cooperatively configuring a converter valve submodule and a bypass switch according to claim 6, characterized in that: The step of 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 working condition is greater than the preset limit current value, then the inductance increase value of the inductor is obtained 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, then obtaining the actual peak current and the current rising rate, and obtaining the resistance value increase value and the power increase value of the resistor according to the actual peak current and the current rising rate as the optimization parameters of the reactor unit; The first selection parameter is optimized according to the optimization parameter to obtain the second selection parameter.

10. 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, used for 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 parameter of the reactor unit; A model simulation module, used for simulating a capacitor discharge condition and a bypass switch misclosing condition in the transient analysis model according to the first selection parameter, to obtain a second selection parameter of the reactor unit; A circuit configuration module is used to configure the coordinated circuit of the submodules in the converter valve using the second selection parameters.

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